# *****************************************************************
# *********************** FUNCTION FACTOR**************************
# *****************************************************************
#
#	computes the factorial function for integers.                  
#	and error analysis for the physical sciences", philip r.       
#	bevington, 1969, mCgraw hill (ny:ny)                           
#
#	27-Jan-1993 	R. Williamson	    	Converted to SPP
#

double procedure factor(n)

double sum, fi, fact
int i,n

begin
       fact=1.0
       if (n-1 > 0) {
	    if (n-10 <= 0) {

	# n less than 11 

          do i=2,n {
                fi=i
                fact=fact*fi
	  }

	# n greater than 10 

          } else {
	    	sum=0.0
	    	do i = 11, n {
                fi=i
                sum=sum+dlog(fi)
	    	}
             fact=3628800.0d00*dexp(sum)
          }
       }

return (fact)
end