interpolation test

[AndyAbok]

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Description Adding more unit test for interpolation models - polynomial

[Required] please make sure you checked that

• [ Yes] The project builds without problems on your machine

[Optional]

• [ N/A] Added unit tests regarding the added features

[bvenn]

There are some problems with this PR:

1. Your test is failing because the accuracy of the implemented interpolation is higher than your expectation. If you replace the expected value with -0.1894337636 the test succeeds.
2. Please always check whether the tests fail by calling ./build.cmd runtests.
3. When adding tests add special cases (e.g. values beeing 0, negative, nan ...)
4. Please open a new test list with testList "Interpolation.Polynomial" [...] because at the moment it is in the cubicSpline test list

[AndyAbok]

Okay I have taken note of the comments. Thanks I'll review them.

[bvenn]

@AndyAbok, I added tests for the polynomial coefficients and opened a separate test that was referenced in Main.fs.