fchebyshev_split

pydl.pydlutils.trace.fchebyshev_split(x, m)[source]

Compute the first m Chebyshev polynomials, but modified to allow a split in the baseline at x=0. The intent is to allow a model fit where a constant term is different for positive and negative x.

Parameters:

x : array-like

Compute the Chebyshev polynomials at these abscissa values.

m : int

The number of Chebyshev polynomials to compute. For example, if m = 3, T_0 (x), T_1 (x) and T_2 (x) will be computed.

Returns:

numpy.ndarray