src/java.base/share/classes/java/lang/Math.java

rev 10702 : 4477961: java.lang.Math.toDegrees(double) could be optimized
Summary: Change toDegrees() and toRadians() to multiplication by a compile-time constant.
Reviewed-by: mduigou, shade

*** 121,130 ****
--- 121,142 ----
       * diameter.
       */
      public static final double PI = 3.14159265358979323846;
  
      /**
+      * Constant by which to multiply an angular value in degrees to obtain an
+      * angular value in radians.
+      */
+     private static final double DEGREES_TO_RADIANS = 0.017453292519943295;
+ 
+     /**
+      * Constant by which to multiply an angular value in radians to obtain an
+      * angular value in degrees.
+      */
+     private static final double RADIANS_TO_DEGREES = 57.29577951308232;
+ 
+     /**
       * Returns the trigonometric sine of an angle.  Special cases:
       * <ul><li>If the argument is NaN or an infinity, then the
       * result is NaN.
       * <li>If the argument is zero, then the result is a zero with the
       * same sign as the argument.</ul>
*** 231,241 ****
       * @return  the measurement of the angle {@code angdeg}
       *          in radians.
       * @since   1.2
       */
      public static double toRadians(double angdeg) {
!         return angdeg / 180.0 * PI;
      }
  
      /**
       * Converts an angle measured in radians to an approximately
       * equivalent angle measured in degrees.  The conversion from
--- 243,253 ----
       * @return  the measurement of the angle {@code angdeg}
       *          in radians.
       * @since   1.2
       */
      public static double toRadians(double angdeg) {
!         return angdeg * DEGREES_TO_RADIANS;
      }
  
      /**
       * Converts an angle measured in radians to an approximately
       * equivalent angle measured in degrees.  The conversion from
*** 247,257 ****
       * @return  the measurement of the angle {@code angrad}
       *          in degrees.
       * @since   1.2
       */
      public static double toDegrees(double angrad) {
!         return angrad * 180.0 / PI;
      }
  
      /**
       * Returns Euler's number <i>e</i> raised to the power of a
       * {@code double} value.  Special cases:
--- 259,269 ----
       * @return  the measurement of the angle {@code angrad}
       *          in degrees.
       * @since   1.2
       */
      public static double toDegrees(double angrad) {
!         return angrad * RADIANS_TO_DEGREES;
      }
  
      /**
       * Returns Euler's number <i>e</i> raised to the power of a
       * {@code double} value.  Special cases: