[
https://issues.apache.org/jira/browse/MATH-1138?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14159786#comment-14159786
]
Hank Grabowski commented on MATH-1138:
--------------------------------------
Nevermind, I've modified the tolerances on the test to match those of Octave's
built in functions for the same values. So that is now properly cranked down
to the tolerances for these algorithms for those curve fits. No changes to the
spline interpolator was necessary to match those values.
> BicubicSplineInterpolator is returning incorrect interpolated values
> --------------------------------------------------------------------
>
> Key: MATH-1138
> URL: https://issues.apache.org/jira/browse/MATH-1138
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.3
> Reporter: Adam Bedrossian
> Attachments: Interpolated Values from CM and MatLab.docx
>
>
> I have encountered a use case with the BicubicSplineInterpolator where the
> interpolated values that are being returned seem incorrect. Furthermore, the
> values do not match those generated by MatLab using the interp2 'cubic'
> method.
> Here is a snippet of code that uses the interpolator:
> double[] xValues = new double[] {36, 36.001, 36.002};
> double[] yValues = new double[] {-108.00, -107.999, -107.998};
> double[][] fValues = new double[][] {{1915, 1906, 1931},
> {1877, 1889, 1894},
> {1878, 1873, 1888}};
> BicubicSplineInterpolator interpolator = new
> BicubicSplineInterpolator();
> BicubicSplineInterpolatingFunction interpolatorFunction =
> interpolator.interpolate(xValues, yValues, fValues);
> double[][] results = new double[9][9];
> double x = 36;
> int arrayIndexX = 0, arrayIndexY = 0;
> while(x <= 36.002) {
> double y = -108;
> arrayIndexY = 0;
> while (y <= -107.998) {
> results[arrayIndexX][arrayIndexY] =
> interpolatorFunction.value(x, y);
> System.out.println(results[arrayIndexX][arrayIndexY]);
> y = y + 0.00025;
> arrayIndexY++;
> }
> x = x + 0.00025;
> arrayIndexX++;
> }
> Attached is a grid showing x and y values and the corresponding interpolated
> value from both commons math and MatLab.
> The values produced by commons math are far off from those created by MatLab.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
