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Tom commented on MATH-1471: --------------------------- Sorry, the Apache Commons Math Library is included in the zip file, but under the src folder there is a class called Interpolate.java which implements the BicubicInterpolator in a method. Under tests folder, there is an InterpolateTest.java which contains a unit test for the BicubicInterpolatingFunction. I have uploaded just the java files as well for easier access, Here is the[ pull request link!|https://github.com/apache/commons-math/pull/90] > BicubicInterpolatingFunction not interpolating correctly for non discrete y > value > --------------------------------------------------------------------------------- > > Key: MATH-1471 > URL: https://issues.apache.org/jira/browse/MATH-1471 > Project: Commons Math > Issue Type: Bug > Affects Versions: 3.6.1 > Environment: JDK 1.8.0_181 > Reporter: Tom > Priority: Major > Attachments: ApacheCommonsMathBiInterpolationTests.zip, > Interpolate.java, InterpolateTest.java > > > Upon performing a bicubic interpolation with two point (x0, y0) and (x1, y1), > the returned bicubic interpolating function returned returns the same result > for variations in the estimated y value. > For example, my inputs are (20, 20) and (25, 25) with f(20, 20) = 64 and > f(25, 25) = 6468. > When I get the bicubic interpolating function for this and vary the estimated > x, it works fine. For (21, 20), the function returns 730.016. When I input > (20, 21), the function returns 64, which is f(20, 20). For any y value in > between 20 and 25, the result is 64. This is the case for any function for > which the y estimate is different from the value on the points. > In other instances, it is varying x values that result in the same result > while varying y estimates seem to work as expected. -- This message was sent by Atlassian JIRA (v7.6.3#76005)