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MATH-1343

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Unnecessary recomputation.
This commit is contained in:
Gilles 2016-03-26 02:32:10 +01:00
parent ae2c81ad18
commit b577805347
1 changed files with 3 additions and 13 deletions
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16
src/main/java/org/apache/commons/math4/distribution/BetaDistribution.java
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@ -42,10 +42,8 @@ public class BetaDistribution extends AbstractRealDistribution {
private final double alpha;
/** Second shape parameter. */
private final double beta;
/** Normalizing factor used in density computations.
* updated whenever alpha or beta are changed.
*/
private double z;
/** Normalizing factor used in density computations.*/
private final double z;
/** Inverse cumulative probability accuracy. */
private final double solverAbsoluteAccuracy;
@ -75,7 +73,7 @@ public class BetaDistribution extends AbstractRealDistribution {
double inverseCumAccuracy) {
this.alpha = alpha;
this.beta = beta;
z = Double.NaN;
z = Gamma.logGamma(alpha) + Gamma.logGamma(beta) - Gamma.logGamma(alpha + beta);
solverAbsoluteAccuracy = inverseCumAccuracy;
}
@ -97,13 +95,6 @@ public class BetaDistribution extends AbstractRealDistribution {
return beta;
}
/** Recompute the normalization factor. */
private void recomputeZ() {
if (Double.isNaN(z)) {
z = Gamma.logGamma(alpha) + Gamma.logGamma(beta) - Gamma.logGamma(alpha + beta);
}
}
/** {@inheritDoc} */
@Override
public double density(double x) {
@ -114,7 +105,6 @@ public class BetaDistribution extends AbstractRealDistribution {
/** {@inheritDoc} **/
@Override
public double logDensity(double x) {
recomputeZ();
if (x < 0 || x > 1) {
return Double.NEGATIVE_INFINITY;
} else if (x == 0) {