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