Gili created MATH-1635:
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Summary: AkimaSplineInterpolator overshoots graph
Key: MATH-1635
URL: https://issues.apache.org/jira/browse/MATH-1635
Project: Commons Math
Issue Type: Bug
Affects Versions: 3.6.1
Reporter: Gili
AkimaSplineInterpolator is not supposed to overshoot points on the graph, but
the following testcase seems to show it doing exactly that:
{code:java}
double[] x = {1616326459, 1616326545, 1616326555, 1616326588, 1616326663,
1616326760,
1616326770, 1616326792, 1616326856, 1616326964, 1616327028, 1616327233,
1616327426,
1616327469, 1616327619, 1616327910, 1616328038, 1616328178, 1616328414,
1616328747,
1616328983, 1616329316, 1616329864, 1616329875};
double[] y = {2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0,
2.0, 2.0, 2.0, 2.0, 2.0,
2.0, 2.0, 2.0, 2.0, 2.0, 3.0};
AkimaSplineInterpolator interpolator = new AkimaSplineInterpolator();
PolynomialSplineFunction interpolate = interpolator.interpolate(x, y);
double value = interpolate.value(1616329584);
System.out.println("Interpolated value is: " + value + ". Expected: 2.0");
{code}
When I run the testcase I get
{code:java}
Interpolated value is: -3.9681889999323374. Expected: 2.0 {code}
I am also quite confused about where to find the latest version of this
library. I know that 3.6.1 is very out of date but I am reluctant to depend on
SNAPSHOT dependencies, especially if they sit outside of Maven Central. What do
you recommend?
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