The type of function to be used is set using the parameter BLZFIT (default is POLY for polynomial).
When BLZFIT=POLY then the number of coefficients should be set to degree of polynomial + 1.
When BLZFIT=SPLINE the number of coefficients should be set to 2 x (number of knots + 7).
When BLZFIT=MEDIAN the number of coefficients should be set to the number of pixels over which a local median value of the blaze function is to be found.
For example, setting BLZ_NPOLY to 4 would permit the fitting of polynomials of the form:
constant + ax + bx squared + cx cubed
Initial suggested value: 7.