pfuimap.f

一个有用的分子动力学小辅助程序

	subroutine pfuimap(ntab, atumin, atumax, datui, tu, ipow, oner,
     $                     ntab2,atumin2,atumax2,datui2,tu2,icode)

	implicit none
*	   ARGUMENTS
	integer ntab,ntab2,ipow,icode
	logical oner
	double precision atumin,atumax,datui,atumin2,atumax2,datui2
	double precision tu(ntab),tu2(ntab2)
*	   PARAMETERS
	double precision zero,one
	parameter (zero=0.d0,one=1.d0)
*	   LOCAL
	integer itab2,mmm
	double precision powi,datu2,arg2,arg,xxx,ddd,value

	if (ipow.lt.1) then
	   icode = 1
	   return
	endif
	powi = one/ipow
	atumin2 = atumin**ipow
	atumax2 = atumax**ipow
	datu2   = (atumax2-atumin2) / (ntab2-1)
	datui2  = one/datu2
	do itab2=1,ntab2
	   arg2 = atumin2 + datu2*(itab2-1)
	   if (arg2.lt.zero) then
	      icode = 2
	      return
	   endif
	   if (ipow.eq.2) then
*	         most cases
	      arg = sqrt(arg2)
	   else
	      arg = arg2**powi
	   endif
	   xxx = (arg - atumin)*datui + one
	   mmm = xxx
	   if (mmm.lt.1)      mmm = 1
	   if (mmm.gt.ntab-1) mmm = ntab - 1
	   ddd = xxx - mmm
	   value = tu(mmm+1)*ddd + tu(mmm)*(one-ddd)
	   if (oner) then
	      if (arg.eq.zero) then
*	            just a protection.  this value is supposed to be
*	            very unlikely to be used.
	         tu2(itab2) = zero
	      else
	         tu2(itab2) = - value/arg
	      endif
	   else
	      tu2(itab2) = value
	   endif
	enddo
	icode = 0
	end