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# scipy.interpolate.lagrange

`scipy.interpolate.``lagrange`(x, w)

  Return a Lagrange interpolating polynomial.

  Given two 1-D arrays x and w, returns the Lagrange interpolating polynomial through the points `(x, w)`.

  Warning: This implementation is numerically unstable. Do not expect to be able to use more than about 20 points even if they are chosen optimally.

  Parameters: | x : array_like x represents the x-coordinates of a set of datapoints. w : array_like w represents the y-coordinates of a set of datapoints, i.e. f(x).
  Returns: | lagrange : numpy.poly1d instance The Lagrange interpolating polynomial.