numpy.polynomial.chebyshev.chebmul — NumPy v1.11 Manual (original) (raw)
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])