The GAUSSFIT function computes a non-linear least-squares fit to a function f ( x ) with from three to six unknown parameters. f ( x ) is a linear combination of a Gaussian and a quadratic; the number of terms is controlled by the keyword parameter NTERMS.
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.
Set this keyword equal to an array of starting estimates for the parameters of the equation. If the NTERMS keyword is specified, the ESTIMATES array should have NTERMS elements. If NTERMS is not specified, the ESTIMATES array should have six elements. If the ESTIMATES array is not specified, estimates are calculated by the GAUSSFIT routine.
NTERMS=6 is the default setting. Here, A 0 is the height of the Gaussian, A 1 is the center of the Gaussian, A 2 is the width of the Gaussian, A 3 is the constant term, A 4 is the linear term, and A 5 is the quadratic term.