numpy.polynomial.polynomial.polyder#
- polynomial.polynomial.polyder(c, m=1, scl=1, axis=0)[source]#
Differentiate a polynomial.
Returns the polynomial 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 polynomial
1 + 2*x + 3*x**2
while [[1,2],[1,2]] represents1 + 1*x + 2*y + 2*x*y
if axis=0 isx
and axis=1 isy
.- Parameters:
- carray_like
Array of polynomial coefficients. If c is multidimensional the different axis correspond to different variables with the degree in each axis given by the corresponding index.
- mint, optional
Number of derivatives taken, must be non-negative. (Default: 1)
- sclscalar, 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)- axisint, optional
Axis over which the derivative is taken. (Default: 0).
New in version 1.7.0.
- Returns:
- derndarray
Polynomial coefficients of the derivative.
See also
Examples
>>> from numpy.polynomial import polynomial as P >>> c = (1, 2, 3, 4) >>> P.polyder(c) # (d/dx)(c) array([ 2., 6., 12.]) >>> P.polyder(c, 3) # (d**3/dx**3)(c) array([24.]) >>> P.polyder(c, scl=-1) # (d/d(-x))(c) array([ -2., -6., -12.]) >>> P.polyder(c, 2, -1) # (d**2/d(-x)**2)(c) array([ 6., 24.])