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Posted to commits@commons.apache.org by er...@apache.org on 2013/06/03 15:48:23 UTC
svn commit: r1488992 -
/commons/proper/math/trunk/src/main/java/org/apache/commons/math3/analysis/integration/MidPointIntegrator.java
Author: erans
Date: Mon Jun 3 13:48:23 2013
New Revision: 1488992
URL: http://svn.apache.org/r1488992
Log:
Removed branching.
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math3/analysis/integration/MidPointIntegrator.java
Modified: commons/proper/math/trunk/src/main/java/org/apache/commons/math3/analysis/integration/MidPointIntegrator.java
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math3/analysis/integration/MidPointIntegrator.java?rev=1488992&r1=1488991&r2=1488992&view=diff
==============================================================================
--- commons/proper/math/trunk/src/main/java/org/apache/commons/math3/analysis/integration/MidPointIntegrator.java (original)
+++ commons/proper/math/trunk/src/main/java/org/apache/commons/math3/analysis/integration/MidPointIntegrator.java Mon Jun 3 13:48:23 2013
@@ -105,47 +105,54 @@ public class MidPointIntegrator extends
* arbitrary m sections because this configuration can best utilize the
* already computed values.</p>
*
- * @param n the stage of 1/2 refinement, n = 0 is no refinement
- * @param previousStageResult Result from the previous call to the {@code stage}
- * method. It is unused in the first stage (when {@code n} is equal to 0).
+ * @param n the stage of 1/2 refinement. Must be larger than 0.
+ * @param previousStageResult Result from the previous call to the
+ * {@code stage} method.
+ * @param min Lower bound of the integration interval.
+ * @param diffMaxMin Difference between the lower bound and upper bound
+ * of the integration interval.
* @return the value of n-th stage integral
* @throws TooManyEvaluationsException if the maximal number of evaluations
* is exceeded.
*/
private double stage(final int n,
- double previousStageResult)
+ double previousStageResult,
+ double min,
+ double diffMaxMin)
throws TooManyEvaluationsException {
- final double min = getMin();
- final double diff = getMax() - min;
-
- if (n == 0) {
- final double midPoint = min + 0.5 * diff;
- return diff * computeObjectiveValue(midPoint);
- } else {
- final long np = 1L << (n - 1); // number of new points in this stage
- double sum = 0;
- // spacing between adjacent new points
- final double spacing = diff / np;
- double x = min + 0.5 * spacing; // the first new point
- for (long i = 0; i < np; i++) {
- sum += computeObjectiveValue(x);
- x += spacing;
- }
- // add the new sum to previously calculated result
- return 0.5 * (previousStageResult + sum * spacing);
+ // number of new points in this stage
+ final long np = 1L << (n - 1);
+ double sum = 0;
+
+ // spacing between adjacent new points
+ final double spacing = diffMaxMin / np;
+
+ // the first new point
+ double x = min + 0.5 * spacing;
+ for (long i = 0; i < np; i++) {
+ sum += computeObjectiveValue(x);
+ x += spacing;
}
+ // add the new sum to previously calculated result
+ return 0.5 * (previousStageResult + sum * spacing);
}
+
/** {@inheritDoc} */
protected double doIntegrate()
throws MathIllegalArgumentException, TooManyEvaluationsException, MaxCountExceededException {
- double oldt = stage(0, 0d);
- iterations.incrementCount();
+ final double min = getMin();
+ final double diff = getMax() - min;
+ final double midPoint = min + 0.5 * diff;
+
+ double oldt = diff * computeObjectiveValue(midPoint);
+
while (true) {
+ iterations.incrementCount();
final int i = iterations.getCount();
- final double t = stage(i, oldt);
+ final double t = stage(i, oldt, min, diff);
if (i >= getMinimalIterationCount()) {
final double delta = FastMath.abs(t - oldt);
final double rLimit =
@@ -155,7 +162,6 @@ public class MidPointIntegrator extends
}
}
oldt = t;
- iterations.incrementCount();
}
}