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Use binary search for scanning the table of interpolation intervals.

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git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1488025 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Gilles Sadowski 2013-05-30 21:44:32 +00:00
parent 8543a0056a
commit 76ace5792c
1 changed files with 20 additions and 21 deletions
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41
src/main/java/org/apache/commons/math3/analysis/interpolation/BicubicSplineInterpolatingFunction.java
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@ -16,6 +16,7 @@
*/
package org.apache.commons.math3.analysis.interpolation;
import java.util.Arrays;
import org.apache.commons.math3.analysis.BivariateFunction;
import org.apache.commons.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.exception.NoDataException;
@ -163,13 +164,7 @@ public class BicubicSplineInterpolatingFunction
public double value(double x, double y)
throws OutOfRangeException {
final int i = searchIndex(x, xval);
if (i == -1) {
throw new OutOfRangeException(x, xval[0], xval[xval.length - 1]);
}
final int j = searchIndex(y, yval);
if (j == -1) {
throw new OutOfRangeException(y, yval[0], yval[yval.length - 1]);
}
final double xN = (x - xval[i]) / (xval[i + 1] - xval[i]);
final double yN = (y - yval[j]) / (yval[j + 1] - yval[j]);
@ -258,13 +253,7 @@ public class BicubicSplineInterpolatingFunction
}
final int i = searchIndex(x, xval);
if (i == -1) {
throw new OutOfRangeException(x, xval[0], xval[xval.length - 1]);
}
final int j = searchIndex(y, yval);
if (j == -1) {
throw new OutOfRangeException(y, yval[0], yval[yval.length - 1]);
}
final double xN = (x - xval[i]) / (xval[i + 1] - xval[i]);
final double yN = (y - yval[j]) / (yval[j + 1] - yval[j]);
@ -296,22 +285,32 @@ public class BicubicSplineInterpolatingFunction
* @param c Coordinate.
* @param val Coordinate samples.
* @return the index in {@code val} corresponding to the interval
* containing {@code c}, or {@code -1} if {@code c} is out of the
* containing {@code c}.
* @throws OutOfRangeException if {@code c} is out of the
* range defined by the boundary values of {@code val}.
*/
private int searchIndex(double c, double[] val) {
if (c < val[0]) {
return -1;
final int r = Arrays.binarySearch(val, c);
if (r == -1 ||
r == -val.length) {
throw new OutOfRangeException(c, val[0], val[val.length - 1]);
}
final int max = val.length;
for (int i = 1; i < max; i++) {
if (c <= val[i]) {
return i - 1;
}
if (r < 0) {
// "c" in within an interpolation sub-interval: Return the
// index of the sample at the lower end of the sub-interval.
return -r - 2;
}
final int last = val.length - 1;
if (r == last) {
// "c" is the last sample of the range: Return the index
// of the sample at the lower end of the last sub-interval.
return last - 1;
}
return -1;
// "c" is another sample point.
return r;
}
/**