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numpy.polynomial.polynomial.polyvander(x, deg)
[source] -
Vandermonde matrix of given degree.
Returns the Vandermonde matrix of degree
deg
and sample pointsx
. The Vandermonde matrix is defined bywhere
0 <= i <= deg
. The leading indices ofV
index the elements ofx
and the last index is the power ofx
.If
c
is a 1-D array of coefficients of lengthn + 1
andV
is the matrixV = polyvander(x, n)
, thennp.dot(V, c)
andpolyval(x, c)
are the same up to roundoff. This equivalence is useful both for least squares fitting and for the evaluation of a large number of polynomials of the same degree and sample points.Parameters: x : array_like
Array of points. The dtype is converted to float64 or complex128 depending on whether any of the elements are complex. If
x
is scalar it is converted to a 1-D array.deg : int
Degree of the resulting matrix.
Returns: vander : ndarray.
The Vandermonde matrix. The shape of the returned matrix is
x.shape + (deg + 1,)
, where the last index is the power ofx
. The dtype will be the same as the convertedx
.See also
numpy.polynomial.polynomial.polyvander()
2017-01-10 18:17:50
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