numpy.polynomial.chebyshev.chebder¶

numpy.polynomial.chebyshev.
chebder
(c, m=1, scl=1, axis=0)[source]¶ Differentiate a Chebyshev series.
Returns the Chebyshev series coefficients c differentiated m times along axis. At each iteration the result is multiplied by scl (the scaling factor is for use in a linear change of variable). The argument c is an array of coefficients from low to high degree along each axis, e.g., [1,2,3] represents the series
1*T_0 + 2*T_1 + 3*T_2
while [[1,2],[1,2]] represents1*T_0(x)*T_0(y) + 1*T_1(x)*T_0(y) + 2*T_0(x)*T_1(y) + 2*T_1(x)*T_1(y)
if axis=0 isx
and axis=1 isy
.Parameters: c : array_like
Array of Chebyshev series coefficients. If c is multidimensional the different axis correspond to different variables with the degree in each axis given by the corresponding index.
m : int, optional
Number of derivatives taken, must be nonnegative. (Default: 1)
scl : scalar, optional
Each differentiation is multiplied by scl. The end result is multiplication by
scl**m
. This is for use in a linear change of variable. (Default: 1)axis : int, optional
Axis over which the derivative is taken. (Default: 0).
New in version 1.7.0.
Returns: der : ndarray
Chebyshev series of the derivative.
See also
Notes
In general, the result of differentiating a Cseries needs to be “reprojected” onto the Cseries basis set. Thus, typically, the result of this function is “unintuitive,” albeit correct; see Examples section below.
Examples
>>> from numpy.polynomial import chebyshev as C >>> c = (1,2,3,4) >>> C.chebder(c) array([ 14., 12., 24.]) >>> C.chebder(c,3) array([ 96.]) >>> C.chebder(c,scl=1) array([14., 12., 24.]) >>> C.chebder(c,2,1) array([ 12., 96.])