changeset 10706:47558493c9c0

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
author bpb
date Mon, 22 Sep 2014 16:59:23 -0700
parents 17cd52fd37e0
children 65e0d662d0eb
files src/java.base/share/classes/java/lang/Math.java src/java.base/share/classes/java/lang/StrictMath.java
diffstat 2 files changed, 29 insertions(+), 4 deletions(-) [+]
line wrap: on
line diff
--- a/src/java.base/share/classes/java/lang/Math.java	Thu Sep 18 11:34:14 2014 +0200
+++ b/src/java.base/share/classes/java/lang/Math.java	Mon Sep 22 16:59:23 2014 -0700
@@ -123,6 +123,18 @@
     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.
@@ -233,7 +245,7 @@
      * @since   1.2
      */
     public static double toRadians(double angdeg) {
-        return angdeg / 180.0 * PI;
+        return angdeg * DEGREES_TO_RADIANS;
     }
 
     /**
@@ -249,7 +261,7 @@
      * @since   1.2
      */
     public static double toDegrees(double angrad) {
-        return angrad * 180.0 / PI;
+        return angrad * RADIANS_TO_DEGREES;
     }
 
     /**
--- a/src/java.base/share/classes/java/lang/StrictMath.java	Thu Sep 18 11:34:14 2014 +0200
+++ b/src/java.base/share/classes/java/lang/StrictMath.java	Mon Sep 22 16:59:23 2014 -0700
@@ -98,6 +98,19 @@
     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.
@@ -179,7 +192,7 @@
     public static strictfp double toRadians(double angdeg) {
         // Do not delegate to Math.toRadians(angdeg) because
         // this method has the strictfp modifier.
-        return angdeg / 180.0 * PI;
+        return angdeg * DEGREES_TO_RADIANS;
     }
 
     /**
@@ -196,7 +209,7 @@
     public static strictfp double toDegrees(double angrad) {
         // Do not delegate to Math.toDegrees(angrad) because
         // this method has the strictfp modifier.
-        return angrad * 180.0 / PI;
+        return angrad * RADIANS_TO_DEGREES;
     }
 
     /**