[commons-math] 02/03: MATH-1635: Unit test demonstrating the reported issue.

[erans]

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commit c6094cf9e0f99f71e92e678fef08202fe3301069
Author: Gilles Sadowski <gillese...@gmail.com>
AuthorDate: Wed Dec 1 02:27:51 2021 +0100

    MATH-1635: Unit test demonstrating the reported issue.
    
    Test is set to "@Ignore" since the behaviour may be a known limitation.
---
 .../interpolation/AkimaSplineInterpolatorTest.java | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git 
a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/analysis/interpolation/AkimaSplineInterpolatorTest.java
 
b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/analysis/interpolation/AkimaSplineInterpolatorTest.java
index c59a9bd..aea67a9 100644
--- 
a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/analysis/interpolation/AkimaSplineInterpolatorTest.java
+++ 
b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/analysis/interpolation/AkimaSplineInterpolatorTest.java
@@ -26,12 +26,14 @@ import 
org.apache.commons.math4.legacy.exception.DimensionMismatchException;
 import org.apache.commons.math4.legacy.exception.NonMonotonicSequenceException;
 import org.apache.commons.math4.legacy.exception.NullArgumentException;
 import org.apache.commons.math4.legacy.exception.NumberIsTooSmallException;
+import 
org.apache.commons.math4.legacy.analysis.polynomials.PolynomialSplineFunction;
 import org.apache.commons.rng.UniformRandomProvider;
 import org.apache.commons.rng.simple.RandomSource;
 import org.apache.commons.math4.core.jdkmath.JdkMath;
 import org.apache.commons.numbers.core.Precision;
 import org.junit.Assert;
 import org.junit.Test;
+import org.junit.Ignore;
 
 public class AkimaSplineInterpolatorTest {
     @Test
@@ -160,6 +162,35 @@ public class AkimaSplineInterpolatorTest {
                            maxTolerance );
     }
 
+    // Test currently fails but it is not clear whether
+    //   https://issues.apache.org/jira/browse/MATH-1635
+    // actually describes a bug, or a limitation of the algorithm.
+    @Ignore
+    @Test
+    public void testMath1635() {
+        final double[] x = {
+            5994, 6005, 6555, 6588, 6663,
+            6760, 6770, 6792, 6856, 6964,
+            7028, 7233, 7426, 7469, 7619,
+            7910, 8038, 8178, 8414, 8747,
+            8983, 9316, 9864, 9875
+        };
+
+        final double[] y = {
+            3.0, 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
+        };
+
+        final AkimaSplineInterpolator interpolator = new 
AkimaSplineInterpolator(true);
+        final PolynomialSplineFunction interpolate = 
interpolator.interpolate(x, y);
+        final double value = interpolate.value(9584);
+        final double expected = 2;
+        Assert.assertEquals(expected, value, 1e-4);
+    }
+
     @Test
     public void testOriginalVsModified() {
         final UnivariateFunction f = new UnivariateFunction() {