numpy.polynomial.chebyshev.chebsub

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

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, c2array_like

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

Returns

outndarray

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.])