GammaFunctionTest.java

/**
 * Copyright (C) 2009 - present by OpenGamma Inc. and the OpenGamma group of companies
 * 
 * Please see distribution for license.
 */
package com.opengamma.analytics.math.function.special;

import static org.testng.AssertJUnit.assertEquals;

import org.testng.annotations.Test;

import cern.jet.random.engine.MersenneTwister;
import cern.jet.random.engine.MersenneTwister64;
import cern.jet.random.engine.RandomEngine;

import com.opengamma.analytics.math.function.Function1D;
import com.opengamma.util.test.TestGroup;

/**
 * Test.
 */
@Test(groups = TestGroup.UNIT)
public class GammaFunctionTest {
  private static final RandomEngine RANDOM = new MersenneTwister64(MersenneTwister.DEFAULT_SEED);
  private static final Function1D<Double, Double> GAMMA = new GammaFunction();
  private static final Function1D<Double, Double> LN_GAMMA = new NaturalLogGammaFunction();
  private static final double EPS = 1e-9;

  @Test
  public void test() {
    final double x = RANDOM.nextDouble();
    assertEquals(Math.log(GAMMA.evaluate(x)), LN_GAMMA.evaluate(x), EPS);
  }
}