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removed some condition logic by changing the continued fraction representation. 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@141290 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Brent Worden 2004-06-10 18:34:53 +00:00
parent d83250a890
commit 15aac108f1
1 changed files with 4 additions and 19 deletions
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23
src/java/org/apache/commons/math/special/Gamma.java
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@ -25,7 +25,7 @@ import org.apache.commons.math.util.ContinuedFraction;
* This is a utility class that provides computation methods related to the
* Gamma family of functions.
*
* @version $Revision: 1.19 $ $Date: 2004/06/07 20:30:16 $
* @version $Revision: 1.20 $ $Date: 2004/06/10 18:34:53 $
*/
public class Gamma implements Serializable {
@ -236,30 +236,15 @@ public class Gamma implements Serializable {
// create continued fraction
ContinuedFraction cf = new ContinuedFraction() {
protected double getA(int n, double x) {
double ret;
switch(n) {
case 0: ret = 0.0; break;
default:
ret = ((2.0 * n) - 1.0) - a + x; break;
}
return ret;
return ((2.0 * n) + 1.0) - a + x;
}
protected double getB(int n, double x) {
double ret;
double t;
switch(n) {
case 1: ret = 1.0; break;
default:
t = n - 1.0;
ret = t * (a - t);
break;
}
return ret;
return n * (a - n);
}
};
ret = cf.evaluate(x, epsilon, maxIterations);
ret = 1.0 / cf.evaluate(x, epsilon, maxIterations);
ret = Math.exp(-x + (a * Math.log(x)) - logGamma(a)) * ret;
}