1 /* 2 * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 import java.util.Random; 28 29 30 /** 31 * The class {@code Math} contains methods for performing basic 32 * numeric operations such as the elementary exponential, logarithm, 33 * square root, and trigonometric functions. 34 * 35 * <p>Unlike some of the numeric methods of class 36 * {@code StrictMath}, all implementations of the equivalent 37 * functions of class {@code Math} are not defined to return the 38 * bit-for-bit same results. This relaxation permits 39 * better-performing implementations where strict reproducibility is 40 * not required. 41 * 42 * <p>By default many of the {@code Math} methods simply call 43 * the equivalent method in {@code StrictMath} for their 44 * implementation. Code generators are encouraged to use 45 * platform-specific native libraries or microprocessor instructions, 46 * where available, to provide higher-performance implementations of 47 * {@code Math} methods. Such higher-performance 48 * implementations still must conform to the specification for 49 * {@code Math}. 50 * 51 * <p>The quality of implementation specifications concern two 52 * properties, accuracy of the returned result and monotonicity of the 53 * method. Accuracy of the floating-point {@code Math} methods is 54 * measured in terms of <i>ulps</i>, units in the last place. For a 55 * given floating-point format, an {@linkplain #ulp(double) ulp} of a 56 * specific real number value is the distance between the two 57 * floating-point values bracketing that numerical value. When 58 * discussing the accuracy of a method as a whole rather than at a 59 * specific argument, the number of ulps cited is for the worst-case 60 * error at any argument. If a method always has an error less than 61 * 0.5 ulps, the method always returns the floating-point number 62 * nearest the exact result; such a method is <i>correctly 63 * rounded</i>. A correctly rounded method is generally the best a 64 * floating-point approximation can be; however, it is impractical for 65 * many floating-point methods to be correctly rounded. Instead, for 66 * the {@code Math} class, a larger error bound of 1 or 2 ulps is 67 * allowed for certain methods. Informally, with a 1 ulp error bound, 68 * when the exact result is a representable number, the exact result 69 * should be returned as the computed result; otherwise, either of the 70 * two floating-point values which bracket the exact result may be 71 * returned. For exact results large in magnitude, one of the 72 * endpoints of the bracket may be infinite. Besides accuracy at 73 * individual arguments, maintaining proper relations between the 74 * method at different arguments is also important. Therefore, most 75 * methods with more than 0.5 ulp errors are required to be 76 * <i>semi-monotonic</i>: whenever the mathematical function is 77 * non-decreasing, so is the floating-point approximation, likewise, 78 * whenever the mathematical function is non-increasing, so is the 79 * floating-point approximation. Not all approximations that have 1 80 * ulp accuracy will automatically meet the monotonicity requirements. 81 * 82 * @author unascribed 83 * @author Joseph D. Darcy 84 * @since JDK1.0 85 */ 86 87 public final class Math { 88 89 /** 90 * Don't let anyone instantiate this class. 91 */ 92 private Math() {} 93 94 /** 95 * The {@code double} value that is closer than any other to 96 * <i>e</i>, the base of the natural logarithms. 97 */ 98 public static final double E = 2.7182818284590452354; 99 100 /** 101 * The {@code double} value that is closer than any other to 102 * <i>pi</i>, the ratio of the circumference of a circle to its 103 * diameter. 104 */ 105 public static final double PI = 3.14159265358979323846; 106 107 /** 108 * Returns the trigonometric sine of an angle. Special cases: 109 * <ul><li>If the argument is NaN or an infinity, then the 110 * result is NaN. 111 * <li>If the argument is zero, then the result is a zero with the 112 * same sign as the argument.</ul> 113 * 114 * <p>The computed result must be within 1 ulp of the exact result. 115 * Results must be semi-monotonic. 116 * 117 * @param a an angle, in radians. 118 * @return the sine of the argument. 119 */ 120 public static double sin(double a) { 121 return StrictMath.sin(a); // default impl. delegates to StrictMath 122 } 123 124 /** 125 * Returns the trigonometric cosine of an angle. Special cases: 126 * <ul><li>If the argument is NaN or an infinity, then the 127 * result is NaN.</ul> 128 * 129 * <p>The computed result must be within 1 ulp of the exact result. 130 * Results must be semi-monotonic. 131 * 132 * @param a an angle, in radians. 133 * @return the cosine of the argument. 134 */ 135 public static double cos(double a) { 136 return StrictMath.cos(a); // default impl. delegates to StrictMath 137 } 138 139 /** 140 * Returns the trigonometric tangent of an angle. Special cases: 141 * <ul><li>If the argument is NaN or an infinity, then the result 142 * is NaN. 143 * <li>If the argument is zero, then the result is a zero with the 144 * same sign as the argument.</ul> 145 * 146 * <p>The computed result must be within 1 ulp of the exact result. 147 * Results must be semi-monotonic. 148 * 149 * @param a an angle, in radians. 150 * @return the tangent of the argument. 151 */ 152 public static double tan(double a) { 153 return StrictMath.tan(a); // default impl. delegates to StrictMath 154 } 155 156 /** 157 * Returns the arc sine of a value; the returned angle is in the 158 * range -<i>pi</i>/2 through <i>pi</i>/2. Special cases: 159 * <ul><li>If the argument is NaN or its absolute value is greater 160 * than 1, then the result is NaN. 161 * <li>If the argument is zero, then the result is a zero with the 162 * same sign as the argument.</ul> 163 * 164 * <p>The computed result must be within 1 ulp of the exact result. 165 * Results must be semi-monotonic. 166 * 167 * @param a the value whose arc sine is to be returned. 168 * @return the arc sine of the argument. 169 */ 170 public static double asin(double a) { 171 return StrictMath.asin(a); // default impl. delegates to StrictMath 172 } 173 174 /** 175 * Returns the arc cosine of a value; the returned angle is in the 176 * range 0.0 through <i>pi</i>. Special case: 177 * <ul><li>If the argument is NaN or its absolute value is greater 178 * than 1, then the result is NaN.</ul> 179 * 180 * <p>The computed result must be within 1 ulp of the exact result. 181 * Results must be semi-monotonic. 182 * 183 * @param a the value whose arc cosine is to be returned. 184 * @return the arc cosine of the argument. 185 */ 186 public static double acos(double a) { 187 return StrictMath.acos(a); // default impl. delegates to StrictMath 188 } 189 190 /** 191 * Returns the arc tangent of a value; the returned angle is in the 192 * range -<i>pi</i>/2 through <i>pi</i>/2. Special cases: 193 * <ul><li>If the argument is NaN, then the result is NaN. 194 * <li>If the argument is zero, then the result is a zero with the 195 * same sign as the argument.</ul> 196 * 197 * <p>The computed result must be within 1 ulp of the exact result. 198 * Results must be semi-monotonic. 199 * 200 * @param a the value whose arc tangent is to be returned. 201 * @return the arc tangent of the argument. 202 */ 203 public static double atan(double a) { 204 return StrictMath.atan(a); // default impl. delegates to StrictMath 205 } 206 207 /** 208 * Converts an angle measured in degrees to an approximately 209 * equivalent angle measured in radians. The conversion from 210 * degrees to radians is generally inexact. 211 * 212 * @param angdeg an angle, in degrees 213 * @return the measurement of the angle {@code angdeg} 214 * in radians. 215 * @since 1.2 216 */ 217 public static double toRadians(double angdeg) { 218 return angdeg / 180.0 * PI; 219 } 220 221 /** 222 * Converts an angle measured in radians to an approximately 223 * equivalent angle measured in degrees. The conversion from 224 * radians to degrees is generally inexact; users should 225 * <i>not</i> expect {@code cos(toRadians(90.0))} to exactly 226 * equal {@code 0.0}. 227 * 228 * @param angrad an angle, in radians 229 * @return the measurement of the angle {@code angrad} 230 * in degrees. 231 * @since 1.2 232 */ 233 public static double toDegrees(double angrad) { 234 return angrad * 180.0 / PI; 235 } 236 237 /** 238 * Returns Euler's number <i>e</i> raised to the power of a 239 * {@code double} value. Special cases: 240 * <ul><li>If the argument is NaN, the result is NaN. 241 * <li>If the argument is positive infinity, then the result is 242 * positive infinity. 243 * <li>If the argument is negative infinity, then the result is 244 * positive zero.</ul> 245 * 246 * <p>The computed result must be within 1 ulp of the exact result. 247 * Results must be semi-monotonic. 248 * 249 * @param a the exponent to raise <i>e</i> to. 250 * @return the value <i>e</i><sup>{@code a}</sup>, 251 * where <i>e</i> is the base of the natural logarithms. 252 */ 253 public static double exp(double a) { 254 return StrictMath.exp(a); // default impl. delegates to StrictMath 255 } 256 257 /** 258 * Returns the natural logarithm (base <i>e</i>) of a {@code double} 259 * value. Special cases: 260 * <ul><li>If the argument is NaN or less than zero, then the result 261 * is NaN. 262 * <li>If the argument is positive infinity, then the result is 263 * positive infinity. 264 * <li>If the argument is positive zero or negative zero, then the 265 * result is negative infinity.</ul> 266 * 267 * <p>The computed result must be within 1 ulp of the exact result. 268 * Results must be semi-monotonic. 269 * 270 * @param a a value 271 * @return the value ln {@code a}, the natural logarithm of 272 * {@code a}. 273 */ 274 public static double log(double a) { 275 return StrictMath.log(a); // default impl. delegates to StrictMath 276 } 277 278 /** 279 * Returns the base 10 logarithm of a {@code double} value. 280 * Special cases: 281 * 282 * <ul><li>If the argument is NaN or less than zero, then the result 283 * is NaN. 284 * <li>If the argument is positive infinity, then the result is 285 * positive infinity. 286 * <li>If the argument is positive zero or negative zero, then the 287 * result is negative infinity. 288 * <li> If the argument is equal to 10<sup><i>n</i></sup> for 289 * integer <i>n</i>, then the result is <i>n</i>. 290 * </ul> 291 * 292 * <p>The computed result must be within 1 ulp of the exact result. 293 * Results must be semi-monotonic. 294 * 295 * @param a a value 296 * @return the base 10 logarithm of {@code a}. 297 * @since 1.5 298 */ 299 public static double log10(double a) { 300 return StrictMath.log10(a); // default impl. delegates to StrictMath 301 } 302 303 /** 304 * Returns the correctly rounded positive square root of a 305 * {@code double} value. 306 * Special cases: 307 * <ul><li>If the argument is NaN or less than zero, then the result 308 * is NaN. 309 * <li>If the argument is positive infinity, then the result is positive 310 * infinity. 311 * <li>If the argument is positive zero or negative zero, then the 312 * result is the same as the argument.</ul> 313 * Otherwise, the result is the {@code double} value closest to 314 * the true mathematical square root of the argument value. 315 * 316 * @param a a value. 317 * @return the positive square root of {@code a}. 318 * If the argument is NaN or less than zero, the result is NaN. 319 */ 320 public static double sqrt(double a) { 321 return StrictMath.sqrt(a); // default impl. delegates to StrictMath 322 // Note that hardware sqrt instructions 323 // frequently can be directly used by JITs 324 // and should be much faster than doing 325 // Math.sqrt in software. 326 } 327 328 329 /** 330 * Returns the cube root of a {@code double} value. For 331 * positive finite {@code x}, {@code cbrt(-x) == 332 * -cbrt(x)}; that is, the cube root of a negative value is 333 * the negative of the cube root of that value's magnitude. 334 * 335 * Special cases: 336 * 337 * <ul> 338 * 339 * <li>If the argument is NaN, then the result is NaN. 340 * 341 * <li>If the argument is infinite, then the result is an infinity 342 * with the same sign as the argument. 343 * 344 * <li>If the argument is zero, then the result is a zero with the 345 * same sign as the argument. 346 * 347 * </ul> 348 * 349 * <p>The computed result must be within 1 ulp of the exact result. 350 * 351 * @param a a value. 352 * @return the cube root of {@code a}. 353 * @since 1.5 354 */ 355 public static double cbrt(double a) { 356 return StrictMath.cbrt(a); 357 } 358 359 /** 360 * Computes the remainder operation on two arguments as prescribed 361 * by the IEEE 754 standard. 362 * The remainder value is mathematically equal to 363 * <code>f1 - f2</code> × <i>n</i>, 364 * where <i>n</i> is the mathematical integer closest to the exact 365 * mathematical value of the quotient {@code f1/f2}, and if two 366 * mathematical integers are equally close to {@code f1/f2}, 367 * then <i>n</i> is the integer that is even. If the remainder is 368 * zero, its sign is the same as the sign of the first argument. 369 * Special cases: 370 * <ul><li>If either argument is NaN, or the first argument is infinite, 371 * or the second argument is positive zero or negative zero, then the 372 * result is NaN. 373 * <li>If the first argument is finite and the second argument is 374 * infinite, then the result is the same as the first argument.</ul> 375 * 376 * @param f1 the dividend. 377 * @param f2 the divisor. 378 * @return the remainder when {@code f1} is divided by 379 * {@code f2}. 380 */ 381 public static double IEEEremainder(double f1, double f2) { 382 return StrictMath.IEEEremainder(f1, f2); // delegate to StrictMath 383 } 384 385 /** 386 * Returns the smallest (closest to negative infinity) 387 * {@code double} value that is greater than or equal to the 388 * argument and is equal to a mathematical integer. Special cases: 389 * <ul><li>If the argument value is already equal to a 390 * mathematical integer, then the result is the same as the 391 * argument. <li>If the argument is NaN or an infinity or 392 * positive zero or negative zero, then the result is the same as 393 * the argument. <li>If the argument value is less than zero but 394 * greater than -1.0, then the result is negative zero.</ul> Note 395 * that the value of {@code Math.ceil(x)} is exactly the 396 * value of {@code -Math.floor(-x)}. 397 * 398 * 399 * @param a a value. 400 * @return the smallest (closest to negative infinity) 401 * floating-point value that is greater than or equal to 402 * the argument and is equal to a mathematical integer. 403 */ 404 public static double ceil(double a) { 405 return StrictMath.ceil(a); // default impl. delegates to StrictMath 406 } 407 408 /** 409 * Returns the largest (closest to positive infinity) 410 * {@code double} value that is less than or equal to the 411 * argument and is equal to a mathematical integer. Special cases: 412 * <ul><li>If the argument value is already equal to a 413 * mathematical integer, then the result is the same as the 414 * argument. <li>If the argument is NaN or an infinity or 415 * positive zero or negative zero, then the result is the same as 416 * the argument.</ul> 417 * 418 * @param a a value. 419 * @return the largest (closest to positive infinity) 420 * floating-point value that less than or equal to the argument 421 * and is equal to a mathematical integer. 422 */ 423 public static double floor(double a) { 424 return StrictMath.floor(a); // default impl. delegates to StrictMath 425 } 426 427 /** 428 * Returns the {@code double} value that is closest in value 429 * to the argument and is equal to a mathematical integer. If two 430 * {@code double} values that are mathematical integers are 431 * equally close, the result is the integer value that is 432 * even. Special cases: 433 * <ul><li>If the argument value is already equal to a mathematical 434 * integer, then the result is the same as the argument. 435 * <li>If the argument is NaN or an infinity or positive zero or negative 436 * zero, then the result is the same as the argument.</ul> 437 * 438 * @param a a {@code double} value. 439 * @return the closest floating-point value to {@code a} that is 440 * equal to a mathematical integer. 441 */ 442 public static double rint(double a) { 443 return StrictMath.rint(a); // default impl. delegates to StrictMath 444 } 445 446 /** 447 * Returns the angle <i>theta</i> from the conversion of rectangular 448 * coordinates ({@code x}, {@code y}) to polar 449 * coordinates (r, <i>theta</i>). 450 * This method computes the phase <i>theta</i> by computing an arc tangent 451 * of {@code y/x} in the range of -<i>pi</i> to <i>pi</i>. Special 452 * cases: 453 * <ul><li>If either argument is NaN, then the result is NaN. 454 * <li>If the first argument is positive zero and the second argument 455 * is positive, or the first argument is positive and finite and the 456 * second argument is positive infinity, then the result is positive 457 * zero. 458 * <li>If the first argument is negative zero and the second argument 459 * is positive, or the first argument is negative and finite and the 460 * second argument is positive infinity, then the result is negative zero. 461 * <li>If the first argument is positive zero and the second argument 462 * is negative, or the first argument is positive and finite and the 463 * second argument is negative infinity, then the result is the 464 * {@code double} value closest to <i>pi</i>. 465 * <li>If the first argument is negative zero and the second argument 466 * is negative, or the first argument is negative and finite and the 467 * second argument is negative infinity, then the result is the 468 * {@code double} value closest to -<i>pi</i>. 469 * <li>If the first argument is positive and the second argument is 470 * positive zero or negative zero, or the first argument is positive 471 * infinity and the second argument is finite, then the result is the 472 * {@code double} value closest to <i>pi</i>/2. 473 * <li>If the first argument is negative and the second argument is 474 * positive zero or negative zero, or the first argument is negative 475 * infinity and the second argument is finite, then the result is the 476 * {@code double} value closest to -<i>pi</i>/2. 477 * <li>If both arguments are positive infinity, then the result is the 478 * {@code double} value closest to <i>pi</i>/4. 479 * <li>If the first argument is positive infinity and the second argument 480 * is negative infinity, then the result is the {@code double} 481 * value closest to 3*<i>pi</i>/4. 482 * <li>If the first argument is negative infinity and the second argument 483 * is positive infinity, then the result is the {@code double} value 484 * closest to -<i>pi</i>/4. 485 * <li>If both arguments are negative infinity, then the result is the 486 * {@code double} value closest to -3*<i>pi</i>/4.</ul> 487 * 488 * <p>The computed result must be within 2 ulps of the exact result. 489 * Results must be semi-monotonic. 490 * 491 * @param y the ordinate coordinate 492 * @param x the abscissa coordinate 493 * @return the <i>theta</i> component of the point 494 * (<i>r</i>, <i>theta</i>) 495 * in polar coordinates that corresponds to the point 496 * (<i>x</i>, <i>y</i>) in Cartesian coordinates. 497 */ 498 public static double atan2(double y, double x) { 499 return StrictMath.atan2(y, x); // default impl. delegates to StrictMath 500 } 501 502 /** 503 * Returns the value of the first argument raised to the power of the 504 * second argument. Special cases: 505 * 506 * <ul><li>If the second argument is positive or negative zero, then the 507 * result is 1.0. 508 * <li>If the second argument is 1.0, then the result is the same as the 509 * first argument. 510 * <li>If the second argument is NaN, then the result is NaN. 511 * <li>If the first argument is NaN and the second argument is nonzero, 512 * then the result is NaN. 513 * 514 * <li>If 515 * <ul> 516 * <li>the absolute value of the first argument is greater than 1 517 * and the second argument is positive infinity, or 518 * <li>the absolute value of the first argument is less than 1 and 519 * the second argument is negative infinity, 520 * </ul> 521 * then the result is positive infinity. 522 * 523 * <li>If 524 * <ul> 525 * <li>the absolute value of the first argument is greater than 1 and 526 * the second argument is negative infinity, or 527 * <li>the absolute value of the 528 * first argument is less than 1 and the second argument is positive 529 * infinity, 530 * </ul> 531 * then the result is positive zero. 532 * 533 * <li>If the absolute value of the first argument equals 1 and the 534 * second argument is infinite, then the result is NaN. 535 * 536 * <li>If 537 * <ul> 538 * <li>the first argument is positive zero and the second argument 539 * is greater than zero, or 540 * <li>the first argument is positive infinity and the second 541 * argument is less than zero, 542 * </ul> 543 * then the result is positive zero. 544 * 545 * <li>If 546 * <ul> 547 * <li>the first argument is positive zero and the second argument 548 * is less than zero, or 549 * <li>the first argument is positive infinity and the second 550 * argument is greater than zero, 551 * </ul> 552 * then the result is positive infinity. 553 * 554 * <li>If 555 * <ul> 556 * <li>the first argument is negative zero and the second argument 557 * is greater than zero but not a finite odd integer, or 558 * <li>the first argument is negative infinity and the second 559 * argument is less than zero but not a finite odd integer, 560 * </ul> 561 * then the result is positive zero. 562 * 563 * <li>If 564 * <ul> 565 * <li>the first argument is negative zero and the second argument 566 * is a positive finite odd integer, or 567 * <li>the first argument is negative infinity and the second 568 * argument is a negative finite odd integer, 569 * </ul> 570 * then the result is negative zero. 571 * 572 * <li>If 573 * <ul> 574 * <li>the first argument is negative zero and the second argument 575 * is less than zero but not a finite odd integer, or 576 * <li>the first argument is negative infinity and the second 577 * argument is greater than zero but not a finite odd integer, 578 * </ul> 579 * then the result is positive infinity. 580 * 581 * <li>If 582 * <ul> 583 * <li>the first argument is negative zero and the second argument 584 * is a negative finite odd integer, or 585 * <li>the first argument is negative infinity and the second 586 * argument is a positive finite odd integer, 587 * </ul> 588 * then the result is negative infinity. 589 * 590 * <li>If the first argument is finite and less than zero 591 * <ul> 592 * <li> if the second argument is a finite even integer, the 593 * result is equal to the result of raising the absolute value of 594 * the first argument to the power of the second argument 595 * 596 * <li>if the second argument is a finite odd integer, the result 597 * is equal to the negative of the result of raising the absolute 598 * value of the first argument to the power of the second 599 * argument 600 * 601 * <li>if the second argument is finite and not an integer, then 602 * the result is NaN. 603 * </ul> 604 * 605 * <li>If both arguments are integers, then the result is exactly equal 606 * to the mathematical result of raising the first argument to the power 607 * of the second argument if that result can in fact be represented 608 * exactly as a {@code double} value.</ul> 609 * 610 * <p>(In the foregoing descriptions, a floating-point value is 611 * considered to be an integer if and only if it is finite and a 612 * fixed point of the method {@link #ceil ceil} or, 613 * equivalently, a fixed point of the method {@link #floor 614 * floor}. A value is a fixed point of a one-argument 615 * method if and only if the result of applying the method to the 616 * value is equal to the value.) 617 * 618 * <p>The computed result must be within 1 ulp of the exact result. 619 * Results must be semi-monotonic. 620 * 621 * @param a the base. 622 * @param b the exponent. 623 * @return the value {@code a}<sup>{@code b}</sup>. 624 */ 625 public static double pow(double a, double b) { 626 return StrictMath.pow(a, b); // default impl. delegates to StrictMath 627 } 628 629 /** 630 * Returns the closest {@code int} to the argument, with ties 631 * rounding up. 632 * 633 * <p> 634 * Special cases: 635 * <ul><li>If the argument is NaN, the result is 0. 636 * <li>If the argument is negative infinity or any value less than or 637 * equal to the value of {@code Integer.MIN_VALUE}, the result is 638 * equal to the value of {@code Integer.MIN_VALUE}. 639 * <li>If the argument is positive infinity or any value greater than or 640 * equal to the value of {@code Integer.MAX_VALUE}, the result is 641 * equal to the value of {@code Integer.MAX_VALUE}.</ul> 642 * 643 * @param a a floating-point value to be rounded to an integer. 644 * @return the value of the argument rounded to the nearest 645 * {@code int} value. 646 * @see java.lang.Integer#MAX_VALUE 647 * @see java.lang.Integer#MIN_VALUE 648 */ 649 public static int round(float a) { 650 if (a != 0x1.fffffep-2f) // greatest float value less than 0.5 651 return (int)floor(a + 0.5f); 652 else 653 return 0; 654 } 655 656 /** 657 * Returns the closest {@code long} to the argument, with ties 658 * rounding up. 659 * 660 * <p>Special cases: 661 * <ul><li>If the argument is NaN, the result is 0. 662 * <li>If the argument is negative infinity or any value less than or 663 * equal to the value of {@code Long.MIN_VALUE}, the result is 664 * equal to the value of {@code Long.MIN_VALUE}. 665 * <li>If the argument is positive infinity or any value greater than or 666 * equal to the value of {@code Long.MAX_VALUE}, the result is 667 * equal to the value of {@code Long.MAX_VALUE}.</ul> 668 * 669 * @param a a floating-point value to be rounded to a 670 * {@code long}. 671 * @return the value of the argument rounded to the nearest 672 * {@code long} value. 673 * @see java.lang.Long#MAX_VALUE 674 * @see java.lang.Long#MIN_VALUE 675 */ 676 public static long round(double a) { 677 if (a != 0x1.fffffffffffffp-2) // greatest double value less than 0.5 678 return (long)floor(a + 0.5d); 679 else 680 return 0; 681 } 682 683 private static Random randomNumberGenerator; 684 685 private static synchronized Random initRNG() { 686 Random rnd = randomNumberGenerator; 687 return (rnd == null) ? (randomNumberGenerator = new Random()) : rnd; 688 } 689 690 /** 691 * Returns a {@code double} value with a positive sign, greater 692 * than or equal to {@code 0.0} and less than {@code 1.0}. 693 * Returned values are chosen pseudorandomly with (approximately) 694 * uniform distribution from that range. 695 * 696 * <p>When this method is first called, it creates a single new 697 * pseudorandom-number generator, exactly as if by the expression 698 * 699 * <blockquote>{@code new java.util.Random()}</blockquote> 700 * 701 * This new pseudorandom-number generator is used thereafter for 702 * all calls to this method and is used nowhere else. 703 * 704 * <p>This method is properly synchronized to allow correct use by 705 * more than one thread. However, if many threads need to generate 706 * pseudorandom numbers at a great rate, it may reduce contention 707 * for each thread to have its own pseudorandom-number generator. 708 * 709 * @return a pseudorandom {@code double} greater than or equal 710 * to {@code 0.0} and less than {@code 1.0}. 711 * @see Random#nextDouble() 712 */ 713 public static double random() { 714 Random rnd = randomNumberGenerator; 715 if (rnd == null) rnd = initRNG(); 716 return rnd.nextDouble(); 717 } 718 719 /** 720 * Returns the absolute value of an {@code int} value. 721 * If the argument is not negative, the argument is returned. 722 * If the argument is negative, the negation of the argument is returned. 723 * 724 * <p>Note that if the argument is equal to the value of 725 * {@link Integer#MIN_VALUE}, the most negative representable 726 * {@code int} value, the result is that same value, which is 727 * negative. 728 * 729 * @param a the argument whose absolute value is to be determined 730 * @return the absolute value of the argument. 731 */ 732 public static int abs(int a) { 733 return (a < 0) ? -a : a; 734 } 735 736 /** 737 * Returns the absolute value of a {@code long} value. 738 * If the argument is not negative, the argument is returned. 739 * If the argument is negative, the negation of the argument is returned. 740 * 741 * <p>Note that if the argument is equal to the value of 742 * {@link Long#MIN_VALUE}, the most negative representable 743 * {@code long} value, the result is that same value, which 744 * is negative. 745 * 746 * @param a the argument whose absolute value is to be determined 747 * @return the absolute value of the argument. 748 */ 749 public static long abs(long a) { 750 return (a < 0) ? -a : a; 751 } 752 753 /** 754 * Returns the absolute value of a {@code float} value. 755 * If the argument is not negative, the argument is returned. 756 * If the argument is negative, the negation of the argument is returned. 757 * Special cases: 758 * <ul><li>If the argument is positive zero or negative zero, the 759 * result is positive zero. 760 * <li>If the argument is infinite, the result is positive infinity. 761 * <li>If the argument is NaN, the result is NaN.</ul> 762 * In other words, the result is the same as the value of the expression: 763 * <p>{@code Float.intBitsToFloat(0x7fffffff & Float.floatToIntBits(a))} 764 * 765 * @param a the argument whose absolute value is to be determined 766 * @return the absolute value of the argument. 767 */ 768 public static float abs(float a) { 769 return (a <= 0.0F) ? 0.0F - a : a; 770 } 771 772 /** 773 * Returns the absolute value of a {@code double} value. 774 * If the argument is not negative, the argument is returned. 775 * If the argument is negative, the negation of the argument is returned. 776 * Special cases: 777 * <ul><li>If the argument is positive zero or negative zero, the result 778 * is positive zero. 779 * <li>If the argument is infinite, the result is positive infinity. 780 * <li>If the argument is NaN, the result is NaN.</ul> 781 * In other words, the result is the same as the value of the expression: 782 * <p>{@code Double.longBitsToDouble((Double.doubleToLongBits(a)<<1)>>>1)} 783 * 784 * @param a the argument whose absolute value is to be determined 785 * @return the absolute value of the argument. 786 */ 787 public static double abs(double a) { 788 return (a <= 0.0D) ? 0.0D - a : a; 789 } 790 791 /** 792 * Returns the greater of two {@code int} values. That is, the 793 * result is the argument closer to the value of 794 * {@link Integer#MAX_VALUE}. If the arguments have the same value, 795 * the result is that same value. 796 * 797 * @param a an argument. 798 * @param b another argument. 799 * @return the larger of {@code a} and {@code b}. 800 */ 801 public static int max(int a, int b) { 802 return (a >= b) ? a : b; 803 } 804 805 /** 806 * Returns the greater of two {@code long} values. That is, the 807 * result is the argument closer to the value of 808 * {@link Long#MAX_VALUE}. If the arguments have the same value, 809 * the result is that same value. 810 * 811 * @param a an argument. 812 * @param b another argument. 813 * @return the larger of {@code a} and {@code b}. 814 */ 815 public static long max(long a, long b) { 816 return (a >= b) ? a : b; 817 } 818 819 private static long negativeZeroFloatBits = Float.floatToIntBits(-0.0f); 820 private static long negativeZeroDoubleBits = Double.doubleToLongBits(-0.0d); 821 822 /** 823 * Returns the greater of two {@code float} values. That is, 824 * the result is the argument closer to positive infinity. If the 825 * arguments have the same value, the result is that same 826 * value. If either value is NaN, then the result is NaN. Unlike 827 * the numerical comparison operators, this method considers 828 * negative zero to be strictly smaller than positive zero. If one 829 * argument is positive zero and the other negative zero, the 830 * result is positive zero. 831 * 832 * @param a an argument. 833 * @param b another argument. 834 * @return the larger of {@code a} and {@code b}. 835 */ 836 public static float max(float a, float b) { 837 if (a != a) return a; // a is NaN 838 if ((a == 0.0f) && (b == 0.0f) 839 && (Float.floatToIntBits(a) == negativeZeroFloatBits)) { 840 return b; 841 } 842 return (a >= b) ? a : b; 843 } 844 845 /** 846 * Returns the greater of two {@code double} values. That 847 * is, the result is the argument closer to positive infinity. If 848 * the arguments have the same value, the result is that same 849 * value. If either value is NaN, then the result is NaN. Unlike 850 * the numerical comparison operators, this method considers 851 * negative zero to be strictly smaller than positive zero. If one 852 * argument is positive zero and the other negative zero, the 853 * result is positive zero. 854 * 855 * @param a an argument. 856 * @param b another argument. 857 * @return the larger of {@code a} and {@code b}. 858 */ 859 public static double max(double a, double b) { 860 if (a != a) return a; // a is NaN 861 if ((a == 0.0d) && (b == 0.0d) 862 && (Double.doubleToLongBits(a) == negativeZeroDoubleBits)) { 863 return b; 864 } 865 return (a >= b) ? a : b; 866 } 867 868 /** 869 * Returns the smaller of two {@code int} values. That is, 870 * the result the argument closer to the value of 871 * {@link Integer#MIN_VALUE}. If the arguments have the same 872 * value, the result is that same value. 873 * 874 * @param a an argument. 875 * @param b another argument. 876 * @return the smaller of {@code a} and {@code b}. 877 */ 878 public static int min(int a, int b) { 879 return (a <= b) ? a : b; 880 } 881 882 /** 883 * Returns the smaller of two {@code long} values. That is, 884 * the result is the argument closer to the value of 885 * {@link Long#MIN_VALUE}. If the arguments have the same 886 * value, the result is that same value. 887 * 888 * @param a an argument. 889 * @param b another argument. 890 * @return the smaller of {@code a} and {@code b}. 891 */ 892 public static long min(long a, long b) { 893 return (a <= b) ? a : b; 894 } 895 896 /** 897 * Returns the smaller of two {@code float} values. That is, 898 * the result is the value closer to negative infinity. If the 899 * arguments have the same value, the result is that same 900 * value. If either value is NaN, then the result is NaN. Unlike 901 * the numerical comparison operators, this method considers 902 * negative zero to be strictly smaller than positive zero. If 903 * one argument is positive zero and the other is negative zero, 904 * the result is negative zero. 905 * 906 * @param a an argument. 907 * @param b another argument. 908 * @return the smaller of {@code a} and {@code b}. 909 */ 910 public static float min(float a, float b) { 911 if (a != a) return a; // a is NaN 912 if ((a == 0.0f) && (b == 0.0f) 913 && (Float.floatToIntBits(b) == negativeZeroFloatBits)) { 914 return b; 915 } 916 return (a <= b) ? a : b; 917 } 918 919 /** 920 * Returns the smaller of two {@code double} values. That 921 * is, the result is the value closer to negative infinity. If the 922 * arguments have the same value, the result is that same 923 * value. If either value is NaN, then the result is NaN. Unlike 924 * the numerical comparison operators, this method considers 925 * negative zero to be strictly smaller than positive zero. If one 926 * argument is positive zero and the other is negative zero, the 927 * result is negative zero. 928 * 929 * @param a an argument. 930 * @param b another argument. 931 * @return the smaller of {@code a} and {@code b}. 932 */ 933 public static double min(double a, double b) { 934 if (a != a) return a; // a is NaN 935 if ((a == 0.0d) && (b == 0.0d) 936 && (Double.doubleToLongBits(b) == negativeZeroDoubleBits)) { 937 return b; 938 } 939 return (a <= b) ? a : b; 940 } 941 942 /** 943 * Returns the size of an ulp of the argument. An ulp, unit in 944 * the last place, of a {@code double} value is the positive 945 * distance between this floating-point value and the {@code 946 * double} value next larger in magnitude. Note that for non-NaN 947 * <i>x</i>, <code>ulp(-<i>x</i>) == ulp(<i>x</i>)</code>. 948 * 949 * <p>Special Cases: 950 * <ul> 951 * <li> If the argument is NaN, then the result is NaN. 952 * <li> If the argument is positive or negative infinity, then the 953 * result is positive infinity. 954 * <li> If the argument is positive or negative zero, then the result is 955 * {@code Double.MIN_VALUE}. 956 * <li> If the argument is ±{@code Double.MAX_VALUE}, then 957 * the result is equal to 2<sup>971</sup>. 958 * </ul> 959 * 960 * @param d the floating-point value whose ulp is to be returned 961 * @return the size of an ulp of the argument 962 * @author Joseph D. Darcy 963 * @since 1.5 964 */ 965 public static double ulp(double d) { 966 return sun.misc.FpUtils.ulp(d); 967 } 968 969 /** 970 * Returns the size of an ulp of the argument. An ulp, unit in 971 * the last place, of a {@code float} value is the positive 972 * distance between this floating-point value and the {@code 973 * float} value next larger in magnitude. Note that for non-NaN 974 * <i>x</i>, <code>ulp(-<i>x</i>) == ulp(<i>x</i>)</code>. 975 * 976 * <p>Special Cases: 977 * <ul> 978 * <li> If the argument is NaN, then the result is NaN. 979 * <li> If the argument is positive or negative infinity, then the 980 * result is positive infinity. 981 * <li> If the argument is positive or negative zero, then the result is 982 * {@code Float.MIN_VALUE}. 983 * <li> If the argument is ±{@code Float.MAX_VALUE}, then 984 * the result is equal to 2<sup>104</sup>. 985 * </ul> 986 * 987 * @param f the floating-point value whose ulp is to be returned 988 * @return the size of an ulp of the argument 989 * @author Joseph D. Darcy 990 * @since 1.5 991 */ 992 public static float ulp(float f) { 993 return sun.misc.FpUtils.ulp(f); 994 } 995 996 /** 997 * Returns the signum function of the argument; zero if the argument 998 * is zero, 1.0 if the argument is greater than zero, -1.0 if the 999 * argument is less than zero. 1000 * 1001 * <p>Special Cases: 1002 * <ul> 1003 * <li> If the argument is NaN, then the result is NaN. 1004 * <li> If the argument is positive zero or negative zero, then the 1005 * result is the same as the argument. 1006 * </ul> 1007 * 1008 * @param d the floating-point value whose signum is to be returned 1009 * @return the signum function of the argument 1010 * @author Joseph D. Darcy 1011 * @since 1.5 1012 */ 1013 public static double signum(double d) { 1014 return sun.misc.FpUtils.signum(d); 1015 } 1016 1017 /** 1018 * Returns the signum function of the argument; zero if the argument 1019 * is zero, 1.0f if the argument is greater than zero, -1.0f if the 1020 * argument is less than zero. 1021 * 1022 * <p>Special Cases: 1023 * <ul> 1024 * <li> If the argument is NaN, then the result is NaN. 1025 * <li> If the argument is positive zero or negative zero, then the 1026 * result is the same as the argument. 1027 * </ul> 1028 * 1029 * @param f the floating-point value whose signum is to be returned 1030 * @return the signum function of the argument 1031 * @author Joseph D. Darcy 1032 * @since 1.5 1033 */ 1034 public static float signum(float f) { 1035 return sun.misc.FpUtils.signum(f); 1036 } 1037 1038 /** 1039 * Returns the hyperbolic sine of a {@code double} value. 1040 * The hyperbolic sine of <i>x</i> is defined to be 1041 * (<i>e<sup>x</sup> - e<sup>-x</sup></i>)/2 1042 * where <i>e</i> is {@linkplain Math#E Euler's number}. 1043 * 1044 * <p>Special cases: 1045 * <ul> 1046 * 1047 * <li>If the argument is NaN, then the result is NaN. 1048 * 1049 * <li>If the argument is infinite, then the result is an infinity 1050 * with the same sign as the argument. 1051 * 1052 * <li>If the argument is zero, then the result is a zero with the 1053 * same sign as the argument. 1054 * 1055 * </ul> 1056 * 1057 * <p>The computed result must be within 2.5 ulps of the exact result. 1058 * 1059 * @param x The number whose hyperbolic sine is to be returned. 1060 * @return The hyperbolic sine of {@code x}. 1061 * @since 1.5 1062 */ 1063 public static double sinh(double x) { 1064 return StrictMath.sinh(x); 1065 } 1066 1067 /** 1068 * Returns the hyperbolic cosine of a {@code double} value. 1069 * The hyperbolic cosine of <i>x</i> is defined to be 1070 * (<i>e<sup>x</sup> + e<sup>-x</sup></i>)/2 1071 * where <i>e</i> is {@linkplain Math#E Euler's number}. 1072 * 1073 * <p>Special cases: 1074 * <ul> 1075 * 1076 * <li>If the argument is NaN, then the result is NaN. 1077 * 1078 * <li>If the argument is infinite, then the result is positive 1079 * infinity. 1080 * 1081 * <li>If the argument is zero, then the result is {@code 1.0}. 1082 * 1083 * </ul> 1084 * 1085 * <p>The computed result must be within 2.5 ulps of the exact result. 1086 * 1087 * @param x The number whose hyperbolic cosine is to be returned. 1088 * @return The hyperbolic cosine of {@code x}. 1089 * @since 1.5 1090 */ 1091 public static double cosh(double x) { 1092 return StrictMath.cosh(x); 1093 } 1094 1095 /** 1096 * Returns the hyperbolic tangent of a {@code double} value. 1097 * The hyperbolic tangent of <i>x</i> is defined to be 1098 * (<i>e<sup>x</sup> - e<sup>-x</sup></i>)/(<i>e<sup>x</sup> + e<sup>-x</sup></i>), 1099 * in other words, {@linkplain Math#sinh 1100 * sinh(<i>x</i>)}/{@linkplain Math#cosh cosh(<i>x</i>)}. Note 1101 * that the absolute value of the exact tanh is always less than 1102 * 1. 1103 * 1104 * <p>Special cases: 1105 * <ul> 1106 * 1107 * <li>If the argument is NaN, then the result is NaN. 1108 * 1109 * <li>If the argument is zero, then the result is a zero with the 1110 * same sign as the argument. 1111 * 1112 * <li>If the argument is positive infinity, then the result is 1113 * {@code +1.0}. 1114 * 1115 * <li>If the argument is negative infinity, then the result is 1116 * {@code -1.0}. 1117 * 1118 * </ul> 1119 * 1120 * <p>The computed result must be within 2.5 ulps of the exact result. 1121 * The result of {@code tanh} for any finite input must have 1122 * an absolute value less than or equal to 1. Note that once the 1123 * exact result of tanh is within 1/2 of an ulp of the limit value 1124 * of ±1, correctly signed ±{@code 1.0} should 1125 * be returned. 1126 * 1127 * @param x The number whose hyperbolic tangent is to be returned. 1128 * @return The hyperbolic tangent of {@code x}. 1129 * @since 1.5 1130 */ 1131 public static double tanh(double x) { 1132 return StrictMath.tanh(x); 1133 } 1134 1135 /** 1136 * Returns sqrt(<i>x</i><sup>2</sup> +<i>y</i><sup>2</sup>) 1137 * without intermediate overflow or underflow. 1138 * 1139 * <p>Special cases: 1140 * <ul> 1141 * 1142 * <li> If either argument is infinite, then the result 1143 * is positive infinity. 1144 * 1145 * <li> If either argument is NaN and neither argument is infinite, 1146 * then the result is NaN. 1147 * 1148 * </ul> 1149 * 1150 * <p>The computed result must be within 1 ulp of the exact 1151 * result. If one parameter is held constant, the results must be 1152 * semi-monotonic in the other parameter. 1153 * 1154 * @param x a value 1155 * @param y a value 1156 * @return sqrt(<i>x</i><sup>2</sup> +<i>y</i><sup>2</sup>) 1157 * without intermediate overflow or underflow 1158 * @since 1.5 1159 */ 1160 public static double hypot(double x, double y) { 1161 return StrictMath.hypot(x, y); 1162 } 1163 1164 /** 1165 * Returns <i>e</i><sup>x</sup> -1. Note that for values of 1166 * <i>x</i> near 0, the exact sum of 1167 * {@code expm1(x)} + 1 is much closer to the true 1168 * result of <i>e</i><sup>x</sup> than {@code exp(x)}. 1169 * 1170 * <p>Special cases: 1171 * <ul> 1172 * <li>If the argument is NaN, the result is NaN. 1173 * 1174 * <li>If the argument is positive infinity, then the result is 1175 * positive infinity. 1176 * 1177 * <li>If the argument is negative infinity, then the result is 1178 * -1.0. 1179 * 1180 * <li>If the argument is zero, then the result is a zero with the 1181 * same sign as the argument. 1182 * 1183 * </ul> 1184 * 1185 * <p>The computed result must be within 1 ulp of the exact result. 1186 * Results must be semi-monotonic. The result of 1187 * {@code expm1} for any finite input must be greater than or 1188 * equal to {@code -1.0}. Note that once the exact result of 1189 * <i>e</i><sup>{@code x}</sup> - 1 is within 1/2 1190 * ulp of the limit value -1, {@code -1.0} should be 1191 * returned. 1192 * 1193 * @param x the exponent to raise <i>e</i> to in the computation of 1194 * <i>e</i><sup>{@code x}</sup> -1. 1195 * @return the value <i>e</i><sup>{@code x}</sup> - 1. 1196 * @since 1.5 1197 */ 1198 public static double expm1(double x) { 1199 return StrictMath.expm1(x); 1200 } 1201 1202 /** 1203 * Returns the natural logarithm of the sum of the argument and 1. 1204 * Note that for small values {@code x}, the result of 1205 * {@code log1p(x)} is much closer to the true result of ln(1 1206 * + {@code x}) than the floating-point evaluation of 1207 * {@code log(1.0+x)}. 1208 * 1209 * <p>Special cases: 1210 * 1211 * <ul> 1212 * 1213 * <li>If the argument is NaN or less than -1, then the result is 1214 * NaN. 1215 * 1216 * <li>If the argument is positive infinity, then the result is 1217 * positive infinity. 1218 * 1219 * <li>If the argument is negative one, then the result is 1220 * negative infinity. 1221 * 1222 * <li>If the argument is zero, then the result is a zero with the 1223 * same sign as the argument. 1224 * 1225 * </ul> 1226 * 1227 * <p>The computed result must be within 1 ulp of the exact result. 1228 * Results must be semi-monotonic. 1229 * 1230 * @param x a value 1231 * @return the value ln({@code x} + 1), the natural 1232 * log of {@code x} + 1 1233 * @since 1.5 1234 */ 1235 public static double log1p(double x) { 1236 return StrictMath.log1p(x); 1237 } 1238 1239 /** 1240 * Returns the first floating-point argument with the sign of the 1241 * second floating-point argument. Note that unlike the {@link 1242 * StrictMath#copySign(double, double) StrictMath.copySign} 1243 * method, this method does not require NaN {@code sign} 1244 * arguments to be treated as positive values; implementations are 1245 * permitted to treat some NaN arguments as positive and other NaN 1246 * arguments as negative to allow greater performance. 1247 * 1248 * @param magnitude the parameter providing the magnitude of the result 1249 * @param sign the parameter providing the sign of the result 1250 * @return a value with the magnitude of {@code magnitude} 1251 * and the sign of {@code sign}. 1252 * @since 1.6 1253 */ 1254 public static double copySign(double magnitude, double sign) { 1255 return sun.misc.FpUtils.rawCopySign(magnitude, sign); 1256 } 1257 1258 /** 1259 * Returns the first floating-point argument with the sign of the 1260 * second floating-point argument. Note that unlike the {@link 1261 * StrictMath#copySign(float, float) StrictMath.copySign} 1262 * method, this method does not require NaN {@code sign} 1263 * arguments to be treated as positive values; implementations are 1264 * permitted to treat some NaN arguments as positive and other NaN 1265 * arguments as negative to allow greater performance. 1266 * 1267 * @param magnitude the parameter providing the magnitude of the result 1268 * @param sign the parameter providing the sign of the result 1269 * @return a value with the magnitude of {@code magnitude} 1270 * and the sign of {@code sign}. 1271 * @since 1.6 1272 */ 1273 public static float copySign(float magnitude, float sign) { 1274 return sun.misc.FpUtils.rawCopySign(magnitude, sign); 1275 } 1276 1277 /** 1278 * Returns the unbiased exponent used in the representation of a 1279 * {@code float}. Special cases: 1280 * 1281 * <ul> 1282 * <li>If the argument is NaN or infinite, then the result is 1283 * {@link Float#MAX_EXPONENT} + 1. 1284 * <li>If the argument is zero or subnormal, then the result is 1285 * {@link Float#MIN_EXPONENT} -1. 1286 * </ul> 1287 * @param f a {@code float} value 1288 * @return the unbiased exponent of the argument 1289 * @since 1.6 1290 */ 1291 public static int getExponent(float f) { 1292 return sun.misc.FpUtils.getExponent(f); 1293 } 1294 1295 /** 1296 * Returns the unbiased exponent used in the representation of a 1297 * {@code double}. Special cases: 1298 * 1299 * <ul> 1300 * <li>If the argument is NaN or infinite, then the result is 1301 * {@link Double#MAX_EXPONENT} + 1. 1302 * <li>If the argument is zero or subnormal, then the result is 1303 * {@link Double#MIN_EXPONENT} -1. 1304 * </ul> 1305 * @param d a {@code double} value 1306 * @return the unbiased exponent of the argument 1307 * @since 1.6 1308 */ 1309 public static int getExponent(double d) { 1310 return sun.misc.FpUtils.getExponent(d); 1311 } 1312 1313 /** 1314 * Returns the floating-point number adjacent to the first 1315 * argument in the direction of the second argument. If both 1316 * arguments compare as equal the second argument is returned. 1317 * 1318 * <p> 1319 * Special cases: 1320 * <ul> 1321 * <li> If either argument is a NaN, then NaN is returned. 1322 * 1323 * <li> If both arguments are signed zeros, {@code direction} 1324 * is returned unchanged (as implied by the requirement of 1325 * returning the second argument if the arguments compare as 1326 * equal). 1327 * 1328 * <li> If {@code start} is 1329 * ±{@link Double#MIN_VALUE} and {@code direction} 1330 * has a value such that the result should have a smaller 1331 * magnitude, then a zero with the same sign as {@code start} 1332 * is returned. 1333 * 1334 * <li> If {@code start} is infinite and 1335 * {@code direction} has a value such that the result should 1336 * have a smaller magnitude, {@link Double#MAX_VALUE} with the 1337 * same sign as {@code start} is returned. 1338 * 1339 * <li> If {@code start} is equal to ± 1340 * {@link Double#MAX_VALUE} and {@code direction} has a 1341 * value such that the result should have a larger magnitude, an 1342 * infinity with same sign as {@code start} is returned. 1343 * </ul> 1344 * 1345 * @param start starting floating-point value 1346 * @param direction value indicating which of 1347 * {@code start}'s neighbors or {@code start} should 1348 * be returned 1349 * @return The floating-point number adjacent to {@code start} in the 1350 * direction of {@code direction}. 1351 * @since 1.6 1352 */ 1353 public static double nextAfter(double start, double direction) { 1354 return sun.misc.FpUtils.nextAfter(start, direction); 1355 } 1356 1357 /** 1358 * Returns the floating-point number adjacent to the first 1359 * argument in the direction of the second argument. If both 1360 * arguments compare as equal a value equivalent to the second argument 1361 * is returned. 1362 * 1363 * <p> 1364 * Special cases: 1365 * <ul> 1366 * <li> If either argument is a NaN, then NaN is returned. 1367 * 1368 * <li> If both arguments are signed zeros, a value equivalent 1369 * to {@code direction} is returned. 1370 * 1371 * <li> If {@code start} is 1372 * ±{@link Float#MIN_VALUE} and {@code direction} 1373 * has a value such that the result should have a smaller 1374 * magnitude, then a zero with the same sign as {@code start} 1375 * is returned. 1376 * 1377 * <li> If {@code start} is infinite and 1378 * {@code direction} has a value such that the result should 1379 * have a smaller magnitude, {@link Float#MAX_VALUE} with the 1380 * same sign as {@code start} is returned. 1381 * 1382 * <li> If {@code start} is equal to ± 1383 * {@link Float#MAX_VALUE} and {@code direction} has a 1384 * value such that the result should have a larger magnitude, an 1385 * infinity with same sign as {@code start} is returned. 1386 * </ul> 1387 * 1388 * @param start starting floating-point value 1389 * @param direction value indicating which of 1390 * {@code start}'s neighbors or {@code start} should 1391 * be returned 1392 * @return The floating-point number adjacent to {@code start} in the 1393 * direction of {@code direction}. 1394 * @since 1.6 1395 */ 1396 public static float nextAfter(float start, double direction) { 1397 return sun.misc.FpUtils.nextAfter(start, direction); 1398 } 1399 1400 /** 1401 * Returns the floating-point value adjacent to {@code d} in 1402 * the direction of positive infinity. This method is 1403 * semantically equivalent to {@code nextAfter(d, 1404 * Double.POSITIVE_INFINITY)}; however, a {@code nextUp} 1405 * implementation may run faster than its equivalent 1406 * {@code nextAfter} call. 1407 * 1408 * <p>Special Cases: 1409 * <ul> 1410 * <li> If the argument is NaN, the result is NaN. 1411 * 1412 * <li> If the argument is positive infinity, the result is 1413 * positive infinity. 1414 * 1415 * <li> If the argument is zero, the result is 1416 * {@link Double#MIN_VALUE} 1417 * 1418 * </ul> 1419 * 1420 * @param d starting floating-point value 1421 * @return The adjacent floating-point value closer to positive 1422 * infinity. 1423 * @since 1.6 1424 */ 1425 public static double nextUp(double d) { 1426 return sun.misc.FpUtils.nextUp(d); 1427 } 1428 1429 /** 1430 * Returns the floating-point value adjacent to {@code f} in 1431 * the direction of positive infinity. This method is 1432 * semantically equivalent to {@code nextAfter(f, 1433 * Float.POSITIVE_INFINITY)}; however, a {@code nextUp} 1434 * implementation may run faster than its equivalent 1435 * {@code nextAfter} call. 1436 * 1437 * <p>Special Cases: 1438 * <ul> 1439 * <li> If the argument is NaN, the result is NaN. 1440 * 1441 * <li> If the argument is positive infinity, the result is 1442 * positive infinity. 1443 * 1444 * <li> If the argument is zero, the result is 1445 * {@link Float#MIN_VALUE} 1446 * 1447 * </ul> 1448 * 1449 * @param f starting floating-point value 1450 * @return The adjacent floating-point value closer to positive 1451 * infinity. 1452 * @since 1.6 1453 */ 1454 public static float nextUp(float f) { 1455 return sun.misc.FpUtils.nextUp(f); 1456 } 1457 1458 1459 /** 1460 * Return {@code d} × 1461 * 2<sup>{@code scaleFactor}</sup> rounded as if performed 1462 * by a single correctly rounded floating-point multiply to a 1463 * member of the double value set. See the Java 1464 * Language Specification for a discussion of floating-point 1465 * value sets. If the exponent of the result is between {@link 1466 * Double#MIN_EXPONENT} and {@link Double#MAX_EXPONENT}, the 1467 * answer is calculated exactly. If the exponent of the result 1468 * would be larger than {@code Double.MAX_EXPONENT}, an 1469 * infinity is returned. Note that if the result is subnormal, 1470 * precision may be lost; that is, when {@code scalb(x, n)} 1471 * is subnormal, {@code scalb(scalb(x, n), -n)} may not equal 1472 * <i>x</i>. When the result is non-NaN, the result has the same 1473 * sign as {@code d}. 1474 * 1475 * <p>Special cases: 1476 * <ul> 1477 * <li> If the first argument is NaN, NaN is returned. 1478 * <li> If the first argument is infinite, then an infinity of the 1479 * same sign is returned. 1480 * <li> If the first argument is zero, then a zero of the same 1481 * sign is returned. 1482 * </ul> 1483 * 1484 * @param d number to be scaled by a power of two. 1485 * @param scaleFactor power of 2 used to scale {@code d} 1486 * @return {@code d} × 2<sup>{@code scaleFactor}</sup> 1487 * @since 1.6 1488 */ 1489 public static double scalb(double d, int scaleFactor) { 1490 return sun.misc.FpUtils.scalb(d, scaleFactor); 1491 } 1492 1493 /** 1494 * Return {@code f} × 1495 * 2<sup>{@code scaleFactor}</sup> rounded as if performed 1496 * by a single correctly rounded floating-point multiply to a 1497 * member of the float value set. See the Java 1498 * Language Specification for a discussion of floating-point 1499 * value sets. If the exponent of the result is between {@link 1500 * Float#MIN_EXPONENT} and {@link Float#MAX_EXPONENT}, the 1501 * answer is calculated exactly. If the exponent of the result 1502 * would be larger than {@code Float.MAX_EXPONENT}, an 1503 * infinity is returned. Note that if the result is subnormal, 1504 * precision may be lost; that is, when {@code scalb(x, n)} 1505 * is subnormal, {@code scalb(scalb(x, n), -n)} may not equal 1506 * <i>x</i>. When the result is non-NaN, the result has the same 1507 * sign as {@code f}. 1508 * 1509 * <p>Special cases: 1510 * <ul> 1511 * <li> If the first argument is NaN, NaN is returned. 1512 * <li> If the first argument is infinite, then an infinity of the 1513 * same sign is returned. 1514 * <li> If the first argument is zero, then a zero of the same 1515 * sign is returned. 1516 * </ul> 1517 * 1518 * @param f number to be scaled by a power of two. 1519 * @param scaleFactor power of 2 used to scale {@code f} 1520 * @return {@code f} × 2<sup>{@code scaleFactor}</sup> 1521 * @since 1.6 1522 */ 1523 public static float scalb(float f, int scaleFactor) { 1524 return sun.misc.FpUtils.scalb(f, scaleFactor); 1525 } 1526 }