numpy.polynomial.polynomial.polyder — NumPy v1.11 Manual (original) (raw)
numpy.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**2while [[1,2],[1,2]] represents 1 + 1*x + 2*y + 2*x*y if axis=0 isx and axis=1 is y.
| Parameters: | c : array_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. m : int, optional Number of derivatives taken, must be non-negative. (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. |
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| Returns: | der : ndarray Polynomial coefficients of the derivative. |
Examples
from numpy.polynomial import polynomial as P c = (1,2,3,4) # 1 + 2x + 3x2 + 4x3 P.polyder(c) # (d/dx)(c) = 2 + 6x + 12x2 array([ 2., 6., 12.]) P.polyder(c,3) # (d3/dx3)(c) = 24 array([ 24.]) P.polyder(c,scl=-1) # (d/d(-x))(c) = -2 - 6x - 12x2 array([ -2., -6., -12.]) P.polyder(c,2,-1) # (d**2/d(-x)**2)(c) = 6 + 24x array([ 6., 24.])