numpy.polynomial.chebyshev.chebsub

numpy.polynomial.chebyshev.chebsub(c1, c2)

Subtract one Chebyshev series from another.

Returns the difference of two Chebyshev series c1 - c2. The sequences of coefficients are from lowest order term to highest, i.e., [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 difference.

See also

chebadd, chebmulx, chebmul, chebdiv, chebpow

Notes

Unlike multiplication, division, etc., the difference of two Chebyshev series is a Chebyshev series (without having to “reproject” the result onto the basis set) so subtraction, just like that of “standard” polynomials, is simply “component-wise.”

Examples

>>> from numpy.polynomial import chebyshev as C
>>> c1 = (1,2,3)
>>> c2 = (3,2,1)
>>> C.chebsub(c1,c2)
array([-2.,  0.,  2.])
>>> C.chebsub(c2,c1) # -C.chebsub(c1,c2)
array([ 2.,  0., -2.])