# jax.numpy.polyvalÂ¶

jax.numpy.polyval(p, x)[source]Â¶

Evaluate a polynomial at specific values.

LAX-backend implementation of polyval(). Original docstring below.

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) â€“

• x (array_like or poly1d object) â€“

Returns

values â€“ If x is a poly1d instance, the result is the composition of the two polynomials, i.e., x is â€śsubstitutedâ€ť in p and the simplified result is returned. In addition, the type of x - array_like or poly1d - governs the type of the output: x array_like => values array_like, x a poly1d object => values is also.

Return type

ndarray or poly1d

See also

poly1d()

A polynomial class.

Notes

Hornerâ€™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.

References

1

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.

Examples

>>> 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.])