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# scipy.interpolate.PchipInterpolator.__call__

`PchipInterpolator.``__call__`(x, nu=0, extrapolate=None)

  Evaluate the piecewise polynomial or its derivative

  Parameters: | x : array_like Points to evaluate the interpolant at. nu : int, optional Order of derivative to evaluate. Must be non-negative. extrapolate : bool, optional Whether to extrapolate to ouf-of-bounds points based on first and last intervals, or to return NaNs.
  Returns: | y : array_like Interpolated values. Shape is determined by replacing the interpolation axis in the original array with the shape of x.

  Notes

  Derivatives are evaluated piecewise for each polynomial segment, even if the polynomial is not differentiable at the breakpoints. The polynomial intervals are considered half-open, `[a, b)`, except for the last interval which is closed `[a, b]`.