c An example of a user defined function

c To modify the "user" function in fitting modify this function
c following the same principles...


c skew triangle function
c parameters are:
c start of fn., mid. point, end of fn. and height
c    a(1)	  a(2)         a(3)          a(4)

	double precision function USER(A, X)
	include 'typecom'

	double precision A(*), X
	if(x.lt.a(1).or.x.gt.a(3))then
c not inside area defined by the triangle
		user=0.0d0
		return
	end if
	if(x.lt.a(2))then
		user=a(4)*(x-a(1))/(a(2)-a(1))
		return
	end if
c ought to be descending bit
		user=a(4)*(1.-(x-a(2))/(a(3)-a(2)))
	end