Previous topic

numpy.polynomial.chebyshev.chebsub

Next topic

numpy.polynomial.chebyshev.chebmulx

This is documentation for an old release of NumPy (version 1.15). Read this page in the documentation of the latest stable release (version 2.2).

numpy.polynomial.chebyshev.chebmul

numpy.polynomial.chebyshev.chebmul(c1, c2)[source]

Multiply one Chebyshev series by another.

Returns the product of two Chebyshev series c1 * c2. The arguments are sequences of coefficients, from lowest order “term” to highest, e.g., [1,2,3] represents the series T_0 + 2*T_1 + 3*T_2.

Parameters:
c1, c2 : array_like

1-D arrays of Chebyshev series coefficients ordered from low to high.

Returns:
out : ndarray

Of Chebyshev series coefficients representing their product.

Notes

In general, the (polynomial) product of two C-series results in terms that are not in the Chebyshev polynomial basis set. Thus, to express the product as a C-series, it is typically necessary to “reproject” the product onto said basis set, which typically produces “unintuitive live” (but correct) results; see Examples section below.

Examples

>>>
>>> from numpy.polynomial import chebyshev as C
>>> c1 = (1,2,3)
>>> c2 = (3,2,1)
>>> C.chebmul(c1,c2) # multiplication requires "reprojection"
array([  6.5,  12. ,  12. ,   4. ,   1.5])