How to Fit a Reference Wave to a Source Wave

Sometimes, you may wish to fit a reference wave to a source wave solely by scaling (multiplying by a factor) and offsetting. Here is an example of the fitting functions needed to accomplish this task. The operations rely on duplicating the reference wave as a global. The fit_ref2src function should only be called through the do_fitref2src function or an equivalent. The function leaves wcoeff containing the scaling and offset.

Function do_fitref2src(wave source, wave reference)
    make/N=2/O/D wcoeff = {1,0}
    duplicate/O reference greference
    FuncFit/Q fit_ref2src, wcoeff, source
    killwaves/Z greference
    return 0
end
 
Function fit_ref2src(wave wc, variable xx) : FitFunc
    wave greference
    return (wc[0]*greference(xx) + wc[1])
end

While simple, I post it for the benefit both of the newcomers to Igor Pro as well as the somewhat seasoned folks such as me who tend to forget such simple things exactly when they are needed.