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From celes...@apache.org
Subject svn commit: r1379253 - /commons/proper/math/trunk/src/test/java/org/apache/commons/math3/special/GammaTest.java
Date Fri, 31 Aug 2012 01:57:50 GMT
Author: celestin
Date: Fri Aug 31 01:57:50 2012
New Revision: 1379253

URL: http://svn.apache.org/viewvc?rev=1379253&view=rev
Log:
MATH-849: unit tests for double Gamma.invGamma1pm1(double).

Modified:
    commons/proper/math/trunk/src/test/java/org/apache/commons/math3/special/GammaTest.java

Modified: commons/proper/math/trunk/src/test/java/org/apache/commons/math3/special/GammaTest.java
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math3/special/GammaTest.java?rev=1379253&r1=1379252&r2=1379253&view=diff
==============================================================================
--- commons/proper/math/trunk/src/test/java/org/apache/commons/math3/special/GammaTest.java
(original)
+++ commons/proper/math/trunk/src/test/java/org/apache/commons/math3/special/GammaTest.java
Fri Aug 31 01:57:50 2012
@@ -17,6 +17,8 @@
 package org.apache.commons.math3.special;
 
 import org.apache.commons.math3.TestUtils;
+import org.apache.commons.math3.exception.NumberIsTooLargeException;
+import org.apache.commons.math3.exception.NumberIsTooSmallException;
 import org.apache.commons.math3.util.FastMath;
 
 import org.junit.Test;
@@ -320,6 +322,75 @@ public class GammaTest {
         }
     }
 
+    /**
+     * <p>
+     * Reference values for the {@link GammaNSWC#invGamma1pm1(double)} method.
+     * These values were generated with the following <a
+     * href="http://maxima.sourceforge.net/">Maxima</a> script
+     * </p>
+     *
+     * <pre>
+     * kill(all);
+     *
+     * fpprec : 64;
+     * gam1(x) := 1 / gamma(1 + x) - 1;
+     * x : makelist(bfloat(i / 8), i, -4, 12);
+     *
+     * for i : 1 while i <= length(x) do print("{",
+     *                                         float(x[i]),
+     *                                         ",",
+     *                                         float(gam1(x[i])),
+     *                                         "},");
+     * </pre>
+     */
+    // @formatter:off
+    private static final double[][] INV_GAMMA1P_M1_REF = {
+        { -0.5 , -.4358104164522437 },
+        { -0.375 , -.3029021533379859 },
+        { -0.25 , -0.183951060901737 },
+        { -0.125 , -.08227611018520711 },
+        { 0.0 , 0.0 },
+        { 0.125 , .06186116458306091 },
+        { 0.25 , .1032626513208373 },
+        { 0.375 , .1249687649039041 },
+        { 0.5 , .1283791670955126 },
+        { 0.625 , .1153565546592225 },
+        { 0.75 , 0.0880652521310173 },
+        { 0.875 , .04882730264547758 },
+        { 1.0 , 0.0 },
+        { 1.125 , -.05612340925950141 },
+        { 1.25 , -.1173898789433302 },
+        { 1.375 , -.1818408982517061 },
+        { 1.5 , -0.247747221936325 },
+    };
+    // @formatter:on
+
+    @Test
+    public void testInvGamma1pm1() {
+
+        final int ulps = 3;
+        for (int i = 0; i < INV_GAMMA1P_M1_REF.length; i++) {
+            final double[] ref = INV_GAMMA1P_M1_REF[i];
+            final double x = ref[0];
+            final double expected = ref[1];
+            final double actual = Gamma.invGamma1pm1(x);
+            final double tol = ulps * FastMath.ulp(expected);
+            Assert.assertEquals(Double.toString(x), expected, actual, tol);
+        }
+    }
+
+    @Test(expected = NumberIsTooSmallException.class)
+    public void testInvGamma1pm1Precondition1() {
+
+        Gamma.invGamma1pm1(-0.51);
+    }
+
+    @Test(expected = NumberIsTooLargeException.class)
+    public void testInvGamma1pm1Precondition2() {
+
+        Gamma.invGamma1pm1(1.51);
+    }
+
     private void checkRelativeError(String msg, double expected, double actual, double tolerance)
{
         Assert.assertEquals(msg, expected, actual, FastMath.abs(tolerance * actual));
     }



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