numpy.polyval(p, x)
[source]
Evaluate a polynomial at specific values.
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 object 1D 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 object A number, an array of numbers, or an instance of poly1d, at which to evaluate |
---|---|
Returns: |
values : ndarray or poly1d If |
See also
poly1d
Horner’s scheme [R70] is used to evaluate the polynomial. Even so, for polynomials of high degree the values may be inaccurate due to rounding errors. Use carefully.
[R70] | (1, 2) I. N. Bronshtein, K. A. Semendyayev, and K. A. Hirsch (Eng. trans. Ed.), Handbook of Mathematics, New York, Van Nostrand Reinhold Co., 1985, pg. 720. |
>>> np.polyval([3,0,1], 5) # 3 * 5**2 + 0 * 5**1 + 1 76 >>> np.polyval([3,0,1], np.poly1d(5)) poly1d([ 76.]) >>> np.polyval(np.poly1d([3,0,1]), 5) 76 >>> np.polyval(np.poly1d([3,0,1]), np.poly1d(5)) poly1d([ 76.])
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https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.polyval.html