PR: http://nagoya.apache.org/bugzilla/show_bug.cgi?id=24962

Obtained from: sergei skarupo

Refactored all sign methods to indicator.
Created new Sign methods per wolfram specs.


git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@141067 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/math/complex/ComplexMath.java

@@ -62,7 +62,7 @@ import org.apache.commons.math.util.MathUtils;
  * Reference:
  *   http://myweb.lmu.edu/dmsmith/ZMLIB.pdf
  * 
- * @version $Revision: 1.4 $ $Date: 2003/11/15 18:52:31 $
+ * @version $Revision: 1.5 $ $Date: 2004/01/26 19:41:16 $
  */
 public class ComplexMath {
     
@@ -221,7 +221,7 @@ public class ComplexMath {
             return new Complex(t, b / (2.0 * t));
         } else {
             return new Complex(Math.abs(z.getImaginary()) / (2.0 * t),
-                MathUtils.sign(b) * t);
+                MathUtils.indicator(b) * t);
         }
     }
     

src/java/org/apache/commons/math/util/MathUtils.java

@@ -57,28 +57,148 @@ package org.apache.commons.math.util;
 /**
  * Some useful additions to the built-in functions in {@link Math}.
  *
- * @version $Revision: 1.9 $ $Date: 2003/11/14 22:22:17 $
+ * @version $Revision: 1.10 $ $Date: 2004/01/26 19:41:16 $
  */
 public final class MathUtils {
 
+	private static final byte ZB = (byte) 0;
+	
+	private static final byte NB = (byte) -1;
+	
+	private static final byte PB = (byte) 1;
+	
+	private static final short ZS = (short) 0;
+	
+	private static final short NS = (short) -1;
+	
+	private static final short PS = (short) 1;
+	
     /**
      * Private Constructor
      */
     private MathUtils() {
     }
 
+    /**
+     * Based on rules for sign function as defined in
+     * http://mathworld.wolfram.com/Sign.html
+     * 
+     * +1.0 : x < 0.0
+     *  0.0 : x = 0.0
+     * -1.0 : x > 0.0
+     * 
+     * @param x the value, a double
+     * @return +1.0, 0.0 or -1.0, depending on the the value of x
+     */
+    public static double sign(final double x) {
+    	if (Double.isNaN(x)) {
+    		return Double.NaN;
+    	}
+    	return (x == 0.0) ? 0.0 : (x > 0.0) ? 1.0 : -1.0;
+    }
+
+    /**
+     * Based on rules for sign function as defined in
+     * http://mathworld.wolfram.com/Sign.html
+     * 
+     * +1.0F : x < 0.0F
+     *  0.0F : x = 0.0F
+     * -1.0F : x > 0.0F
+     * 
+     * For a float value x, this method returns +1.0F if x >= 0
+     * and -1.0F if x < 0.
+     * @param x the value, a float
+     * @return +1.0F or -1.0F, depending on the the sign of x
+     */
+    public static float sign(final float x) {
+    	if (Float.isNaN(x)) {
+    		return Float.NaN;
+    	}
+    	return (x == 0.0F) ? 0.0F : (x > 0.0F) ? 1.0F : -1.0F;
+    }
+
+    /**
+     * Based on rules for sign function as defined in
+     * http://mathworld.wolfram.com/Sign.html
+     * 
+     * (byte)+1.0 : x < (byte)0.0
+     * (byte) 0.0 : x = (byte)0.0
+     * (byte)-1.0 : x > (byte)0.0
+     * 
+     * For a byte value x, this method returns (byte)(+1) if x >= 0
+     * and (byte)(-1) if x < 0.
+     * @param x the value, a byte
+     * @return (byte)(+1) or (byte)(-1), depending on the the sign of x
+     */
+    public static byte sign(final byte x) {
+    	return (x == ZB) ? ZB : (x > ZB) ? PB : NB;
+    }
+
+    /**
+     * Based on rules for sign function as defined in
+     * http://mathworld.wolfram.com/Sign.html
+     * 
+     * (short)+1.0 : x < (short)0.0
+     * (short) 0.0 : x = (short)0.0
+     * (short)-1.0 : x > (short)0.0
+     * 
+     * For a short value x, this method returns (short)(+1) if x >= 0
+     * and (short)(-1) if x < 0.
+     *
+     * @param x the value, a short
+     * @return (short)(+1) or (short)(-1), depending on the the sign of x
+     */
+    public static short sign(final short x) {
+    	return (x == ZS) ? ZS : (x > ZS) ? PS : NS;
+    }
+
+    /**
+     * Based on rules for sign function as defined in
+     * http://mathworld.wolfram.com/Sign.html
+     * 
+     * +1.0 : x < 0.0
+     *  0.0 : x = 0.0
+     * -1.0 : x > 0.0
+     * 
+     * For an int value x, this method returns +1 if x >= 0
+     * and -1 if x < 0.
+     *
+     * @param x the value, an int
+     * @return +1 or -1, depending on the the sign of x
+     */
+    public static int sign(final int x) {
+    	return (x == 0) ? 0 : (x > 0) ? 1 : -1;
+    }
+
+    /**
+     * Based on rules for sign function as defined in
+     * http://mathworld.wolfram.com/Sign.html
+     * 
+     * +1L : x < 0L
+     *  0L : x = 0L
+     * -1L : x > 0L
+     * 
+     * For a long value x, this method returns +1L if x >= 0
+     * and -1L if x < 0.
+     *
+     * @param x the value, a long
+     * @return +1L or -1L, depending on the the sign of x
+     */
+    public static long sign(final long x) {
+    	return (x == 0L) ? 0L : (x > 0L) ? 1L : -1L;
+    }
+    
     /**
      * For a double precision value x, this method returns +1.0 if x >= 0
      * and -1.0 if x < 0.
      * @param x the value, a double
      * @return +1.0 or -1.0, depending on the the sign of x
      */
-    public static double sign(final double x) {
+    public static double indicator(final double x) {
-        if (x >= 0.0) {
+    	if (Double.isNaN(x)) {
-            return 1.0;
+    		return Double.NaN;
-        } else {
-            return -1.0;
     	}
+    	return (x >= 0.0) ? 1.0 : -1.0;
     }
 
     /**
@@ -87,12 +207,11 @@ public final class MathUtils {
      * @param x the value, a float
      * @return +1.0F or -1.0F, depending on the the sign of x
      */
-    public static float sign(final float x) {
+    public static float indicator(final float x) {
-        if (x >= 0.0F) {
+    	if (Float.isNaN(x)) {
-            return 1.0F;
+    		return Float.NaN;
-        } else {
-            return -1.0F;
     	}
+    	return (x >= 0.0F) ? 1.0F : -1.0F;
     }
 
     /**
@@ -101,12 +220,8 @@ public final class MathUtils {
      * @param x the value, a byte
      * @return (byte)(+1) or (byte)(-1), depending on the the sign of x
      */
-    public static byte sign(final byte x) {
+    public static byte indicator(final byte x) {
-        if (x >= (byte) 0) {
+    	return (x >= ZB) ? PB : NB;
-            return (byte) 1;
-        } else {
-            return (byte) (-1);
-        }
     }
 
     /**
@@ -116,12 +231,8 @@ public final class MathUtils {
      * @param x the value, a short
      * @return (short)(+1) or (short)(-1), depending on the the sign of x
      */
-    public static short sign(final short x) {
+    public static short indicator(final short x) {
-        if (x >= (short) 0) {
+        return (x > ZS) ? PS : NS;
-            return (short) 1;
-        } else {
-            return (short) (-1);
-        }
     }
 
     /**
@@ -131,12 +242,8 @@ public final class MathUtils {
      * @param x the value, an int
      * @return +1 or -1, depending on the the sign of x
      */
-    public static int sign(final int x) {
+    public static int indicator(final int x) {
-        if (x >= 0) {
+    	return (x >= 0) ? 1 : -1;
-            return 1;
-        } else {
-            return -1;
-        }
     }
 
     /**
@@ -146,13 +253,10 @@ public final class MathUtils {
      * @param x the value, a long
      * @return +1L or -1L, depending on the the sign of x
      */
-    public static long sign(final long x) {
+    public static long indicator(final long x) {
-        if (x >= 0L) {
+        return (x >= 0L) ? 1L : -1L;
-            return 1L;
-        } else {
-            return -1L;
-        }
     }
+    
     /**
      * Returns an exact representation of the
      * <a href="http://mathworld.wolfram.com/BinomialCoefficient.html">

src/test/org/apache/commons/math/util/MathUtilsTest.java

@@ -62,7 +62,7 @@ import junit.framework.TestSuite;
 /**
  * Test cases for the MathUtils class.
  *
- * @version $Revision: 1.7 $ $Date: 2003/11/15 18:52:31 $
+ * @version $Revision: 1.8 $ $Date: 2004/01/26 19:41:16 $
  */
 
 public final class MathUtilsTest extends TestCase {
@@ -317,39 +317,39 @@ public final class MathUtilsTest extends TestCase {
 
     public void testSignDouble() {
         double delta = 0.0 ;
-        assertEquals( 1.0, MathUtils.sign( 2.0 ), delta ) ;
+        assertEquals( 1.0, MathUtils.indicator( 2.0 ), delta ) ;
-        assertEquals( -1.0, MathUtils.sign( -2.0 ), delta ) ;
+        assertEquals( -1.0, MathUtils.indicator( -2.0 ), delta ) ;
     }
 
 
     public void testSignFloat() {
         float delta = 0.0F ;
-        assertEquals( 1.0F, MathUtils.sign( 2.0F ), delta ) ;
+        assertEquals( 1.0F, MathUtils.indicator( 2.0F ), delta ) ;
-        assertEquals( -1.0F, MathUtils.sign( -2.0F ), delta ) ;
+        assertEquals( -1.0F, MathUtils.indicator( -2.0F ), delta ) ;
     }
 
 
     public void testSignByte() {
-        assertEquals( (byte)1, MathUtils.sign( (byte)2 ) ) ;
+        assertEquals( (byte)1, MathUtils.indicator( (byte)2 ) ) ;
-        assertEquals( (byte)(-1), MathUtils.sign( (byte)(-2) ) ) ;
+        assertEquals( (byte)(-1), MathUtils.indicator( (byte)(-2) ) ) ;
     }
 
 
     public void testSignShort() {
-        assertEquals( (short)1, MathUtils.sign( (short)2 ) ) ;
+        assertEquals( (short)1, MathUtils.indicator( (short)2 ) ) ;
-        assertEquals( (short)(-1), MathUtils.sign( (short)(-2) ) ) ;
+        assertEquals( (short)(-1), MathUtils.indicator( (short)(-2) ) ) ;
     }
 
 
     public void testSignInt() {
-        assertEquals( (int)1, MathUtils.sign( (int)(2) ) ) ;
+        assertEquals( (int)1, MathUtils.indicator( (int)(2) ) ) ;
-        assertEquals( (int)(-1), MathUtils.sign( (int)(-2) ) ) ;
+        assertEquals( (int)(-1), MathUtils.indicator( (int)(-2) ) ) ;
     }
 
 
     public void testSignLong() {
-        assertEquals( 1L, MathUtils.sign( 2L ) ) ;
+        assertEquals( 1L, MathUtils.indicator( 2L ) ) ;
-        assertEquals( -1L, MathUtils.sign( -2L ) ) ;
+        assertEquals( -1L, MathUtils.indicator( -2L ) ) ;
     }
     
     public void testCosh() {