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# numpy.polynomial.chebyshev.chebvander

polynomial.chebyshev.chebvander(x, deg)

  Pseudo-Vandermonde matrix of given degree.

  Returns the pseudo-Vandermonde matrix of degree deg and sample points x. The pseudo-Vandermonde matrix is defined by

  \[V[..., i] = T_i(x),\]

  where `0 <= i <= deg`. The leading indices of V index the elements of x and the last index is the degree of the Chebyshev polynomial.

  If c is a 1-D array of coefficients of length `n + 1` and V is the matrix `V = chebvander(x, n)`, then `np.dot(V, c)` and `chebval(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 Chebyshev series 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 pseudo Vandermonde matrix. The shape of the returned matrix is `x.shape + (deg + 1,)`, where The last index is the degree of the corresponding Chebyshev polynomial. The dtype will be the same as the converted x.