NumPy polymulx()

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The numpy.polymulx function multiplies the polynomial c with a value x which is the independent variable.

carray_like or poly1d objectThe input polynomials to be multiplied

The following table shows the return value of the function:

Return Valuendarray or poly1d objectThe polynomial resulting from the multiplication of the inputs. If either inputs is a poly1d object, then the output is also a poly1d object. Otherwise, it is a 1D array of polynomial coefficients from highest to lowest degree.

Let’s dive into some examples to show how the function is used in practice:


import numpy as np
import numpy.polynomial.polynomial as poly

print(poly.polymulx([0]) == [0])
print(poly.polymulx([1]) == [0, 1])
for i in range(1, 5):
    ser = [0]*i + [1]
    tgt = [0]*(i + 1) + [1]
    print(poly.polymulx(ser) == tgt) 

[ True]
[ True  True]
[ True  True  True]
[ True  True  True  True]
[ True  True  True  True  True]
[ True  True  True  True  True  True]

This function is inspired from this Github repository.

Any master coder has a “hands-on” mentality with a bias towards action. Try it yourself—play with the function in the following interactive code shell:

Exercise: Change the parameters of your polynomials and print them without the comparisons. Do you understand where they come from?

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