[gwt-contrib] Fix implementation of Math.sinh and Math.tanh (external issue 4991) (issue602801)

[rice]

Reviewers: jat,

Description:
Fix implementation of Math.sinh and Math.tanh (external issue 4991)

Please review this at http://gwt-code-reviews.appspot.com/602801/show

Affected files:
  M user/super/com/google/gwt/emul/java/lang/Math.java
  M user/test/com/google/gwt/emultest/java/lang/MathTest.java


Index: user/super/com/google/gwt/emul/java/lang/Math.java
===================================================================
--- user/super/com/google/gwt/emul/java/lang/Math.java  (revision 8240)
+++ user/super/com/google/gwt/emul/java/lang/Math.java  (working copy)
@@ -27,10 +27,12 @@
   private static final double PI_UNDER_180 = 180.0 / PI;

   public static double abs(double x) {
+//    return (x <= 0.0) ? 0.0 - x : x;
     return x < 0 ? -x : x;
   }

   public static float abs(float x) {
+//  return (x <= 0.0) ? 0.0 - x : x;
     return x < 0 ? -x : x;
   }

@@ -253,7 +255,7 @@
   }-*/;

   public static native double sinh(double x) /*-{
-    return Math.sinh(x);
+    return (Math.exp(x) - Math.exp(-x)) / 2.0;
   }-*/;

   public static native double sqrt(double x) /*-{
@@ -265,7 +267,8 @@
   }-*/;

   public static native double tanh(double x) /*-{
-    return Math.tanh(x);
+    var e2x = Math.exp(2.0 * x);
+    return (e2x - 1) / (e2x + 1);
   }-*/;

   public static double toDegrees(double x) {
Index: user/test/com/google/gwt/emultest/java/lang/MathTest.java
===================================================================
--- user/test/com/google/gwt/emultest/java/lang/MathTest.java	(revision  
8240)
+++ user/test/com/google/gwt/emultest/java/lang/MathTest.java   (working copy)
@@ -30,6 +30,17 @@
     return "com.google.gwt.emultest.EmulSuite";
   }

+  public void testAbs() {
+    double v = Math.abs(-1.0);
+    assertEquals(1.0, v);
+    v = Math.abs(1.0);
+    assertEquals(1.0, v);
+    v = Math.abs(-1.0 / Double.POSITIVE_INFINITY); // -0.0
+    assertEquals(0.0, v);
+    v = Math.abs(0.0);
+    assertEquals(0.0, v);
+  }
+
   public void testCbrt() {
     double v = Math.cbrt(1000.0);
     assertEquals(10.0, v, 1e-7);
@@ -44,6 +55,15 @@
     assertEquals(-1.0, v, 1e-7);
     v = Math.cos(Math.PI * 1.5);
     assertEquals(0.0, v, 1e-7);
+  }
+
+  public void testCosh() {
+    double v = Math.cosh(0.0);
+    assertEquals(1.0, v, 1e-7);
+    v = Math.cosh(1.0);
+    assertEquals(1.5430806348, v, 1e-7);
+    v = Math.cosh(-1.0);
+    assertEquals(1.5430806348, v, 1e-7);
   }

   public void testLog() {
@@ -66,4 +86,22 @@
     v = Math.sin(Math.PI * 1.5);
     assertEquals(-1.0, v, 1e-7);
   }
+
+  public void testSinh() {
+    double v = Math.sinh(0.0);
+    assertEquals(0.0, v, 1e-7);
+    v = Math.sinh(1.0);
+    assertEquals(1.175201193, v, 1e-7);
+    v = Math.sinh(-1.0);
+    assertEquals(-1.175201193, v, 1e-7);
+  }
+
+  public void testTanh() {
+    double v = Math.tanh(0.0);
+    assertEquals(0.0, v, 1e-7);
+    v = Math.tanh(1.0);
+    assertEquals(0.761594155, v, 1e-7);
+    v = Math.tanh(-1.0);
+    assertEquals(-0.761594155, v, 1e-7);
+  }
 }


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