Parameters      Defaults
FEXPONENTIAL number         1
             BACKGROUND(bg) 0.0


   Specify a series of linear exponential fit functions
   (aka decay curves) and set start values for the fit parameters.
   The fit function is

      y(x) = p1 + p2 * exp( p3 * x ) + ... + p2n * exp( p2n+1 * x )


      FEXP / BACK(100)

   defines a fit function y(x) = p1 + p2 * exp( p3 * x )
   with p1=100.
   The function is graphed using the startup values for p1,p2,p3.

Parameter NUMBER

The fit function is composed of number linear exponential functions
plus a constant term. If number=* there will be as many exponentials
as there are fit windows.

Parameter BACKGROUND(bg)

The start value bg is assigned to the constant background parameter (p1).

Parameter PROMPT

To estimate start values for the fit parameters lower and upper limits
are prompted by cursor or by terminal input if no cursor is available.
The series of data windows defined this way are used to estimate the
start parameters of the exponential functions.

Parameter NODISP

Don't display exponential curves with start values