bundles / numpy 2.4.4 / numpy / polyval
_ArrayFunctionDispatcher
numpy:polyval
Signature
def polyval ( p , x ) Summary
Evaluate a polynomial at specific values.
Extended Summary
If p is of length N, this function returns the value
p[0]*x**(N-1) + p[1]*x**(N-2) + ... + p[N-2]*x + p[N-1]If x is a sequence, then p(x) is returned for each element of x. If x is another polynomial then the composite polynomial p(x(t)) is returned.
Parameters
p: array_like or poly1d object1D array of polynomial coefficients (including coefficients equal to zero) from highest degree to the constant term, or an instance of poly1d.
x: array_like or poly1d objectA number, an array of numbers, or an instance of poly1d, at which to evaluate
p.
Returns
values: ndarray or poly1dIf
xis a poly1d instance, the result is the composition of the two polynomials, i.e.,xis "substituted" inpand the simplified result is returned. In addition, the type ofx- array_like or poly1d - governs the type of the output:xarray_like => values array_like,xa poly1d object => values is also.
Notes
Horner's scheme [1] is used to evaluate the polynomial. Even so, for polynomials of high degree the values may be inaccurate due to rounding errors. Use carefully.
If x is a subtype of ndarray the return value will be of the same type.
Examples
import numpy as np
✓np.polyval([3,0,1], 5) # 3 * 5**2 + 0 * 5**1 + 1
✗np.polyval([3,0,1], np.poly1d(5))
✓np.polyval(np.poly1d([3,0,1]), 5)
✗np.polyval(np.poly1d([3,0,1]), np.poly1d(5))
✓See also
- poly1d
A polynomial class.
Aliases
-
numpy.polyval