splev#
- scipy.interpolate.splev(x, tck, der=0, ext=0)[source]#
Evaluate a B-spline or its derivatives.
Legacy
This function is considered legacy and will no longer receive updates. While we currently have no plans to remove it, we recommend that new code uses more modern alternatives instead. Specifically, we recommend constructing a
BSpline
object and using its__call__
method.Given the knots and coefficients of a B-spline representation, evaluate the value of the smoothing polynomial and its derivatives. This is a wrapper around the FORTRAN routines splev and splder of FITPACK.
- Parameters:
- xarray_like
An array of points at which to return the value of the smoothed spline or its derivatives. If tck was returned from
splprep
, then the parameter values, u should be given.- tckBSpline instance or tuple
If a tuple, then it should be a sequence of length 3 returned by
splrep
orsplprep
containing the knots, coefficients, and degree of the spline. (Also see Notes.)- derint, optional
The order of derivative of the spline to compute (must be less than or equal to k, the degree of the spline).
- extint, optional
Controls the value returned for elements of
x
not in the interval defined by the knot sequence.if ext=0, return the extrapolated value.
if ext=1, return 0
if ext=2, raise a ValueError
if ext=3, return the boundary value.
The default value is 0.
- Returns:
- yndarray or list of ndarrays
An array of values representing the spline function evaluated at the points in x. If tck was returned from
splprep
, then this is a list of arrays representing the curve in an N-D space.
Notes
Manipulating the tck-tuples directly is not recommended. In new code, prefer using
BSpline
objects.References
[1]C. de Boor, “On calculating with b-splines”, J. Approximation Theory, 6, p.50-62, 1972.
[2]M. G. Cox, “The numerical evaluation of b-splines”, J. Inst. Maths Applics, 10, p.134-149, 1972.
[3]P. Dierckx, “Curve and surface fitting with splines”, Monographs on Numerical Analysis, Oxford University Press, 1993.
Examples
Examples are given in the tutorial.
A comparison between
splev
,splder
andspalde
to compute the derivatives of a B-spline can be found in thespalde
examples section.