numpy.polynomial.chebyshev.chebval

numpy.polynomial.chebyshev.chebval(x, cs)

Evaluate a Chebyshev series.

If cs is of length n, this function returns :

p(x) = cs[0]*T_0(x) + cs[1]*T_1(x) + ... + cs[n-1]*T_{n-1}(x)

If x is a sequence or array then p(x) will have the same shape as x. If r is a ring_like object that supports multiplication and addition by the values in cs, then an object of the same type is returned.

Parameters :

x : array_like, ring_like

Array of numbers or objects that support multiplication and addition with themselves and with the elements of cs.

cs : array_like

1-d array of Chebyshev coefficients ordered from low to high.

Returns :

values : ndarray, ring_like

If the return is an ndarray then it has the same shape as x.

See also

chebfit

Notes

The evaluation uses Clenshaw recursion, aka synthetic division.

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