The Numpy polynomial related function discussed in recent posts can now be downloaded from:
The download file includes Python code and a sample spreadsheet. Required installed software is Python, Numba and pyxll to call the code from Excel. Some of the functions in the default file require the just-in-time compiler, Numba. For those without Numba installed the file pyNumpy-noJIT.py can be used.
Note that the Quadratic, Cubic and Quartic functions (which are not included in Numpy) are based on C code from the following sources:
- http://numerical.recipes/book/book.html
- https://github.com/LuaDist/gsl/blob/master/poly/solve_cubic.c
- https://www.gnu.org/software/gsl/doc/html/poly.html
The screenshots below show examples of the spreadsheet functions: (click on any image for full-size view).
The py_PolyRoots function calls the general purpose Numpy function, that will work for any degree polynomial. The alternative functions have very much better performance for degrees up to quartic.
Py_PolyFromRoots finds polynomial factors from its roots. Py_PolyVal returns the function value for any value of x, allowing array input.
Py_PolyFit fits a polynomial to input data:
Other Numpy polynomial functions are shown below:
The py_flip functions reverses a Numpy array along a specified axis:
Finally functions are provided to form a Numpy array of complex numbers from an Excel list of pairs of floats:
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