Parameters   Defaults

FXCAL offset       0
      factor       1
      /
      CHANNELS(ch)
      XNEW(xn)    
      ERRORS(er)  


Purpose

  Linear calibration of the x-axis.

Example

  FXCAL / chan(100,200) xnew(4.5,7.6)

  Use channels 100 and 200 corresponding to new x-values 4.5 and 7.6.

Specifies directly the calibration polynomial coefficients.
X-values are converted according to  xnew = xold * factor + offset 

Perform analytical least squares fit to obtain calibration coefficients.
Lists of x-, y- and (optionally) y-error-values are given by ch,xn and er, respectively.
The number of values in these lists must be consistent.
If the lists contain only two values each the coefficients are computed as
offset and slope of a straight line.