switch_corn.f90

基于linux操作下的fortran快速付立变换的程序

        subroutine switch_corn(n1dfft,n2,lot,n1,lzt,zt,zw)
        implicit real*8 (a-h,o-z)
        dimension zw(2,lot,n2),zt(2,lzt,n1)
! WARNING: Assuming that high frequencies are in the corners
!          and that n2 is multiple of 4

! Low frequencies
        do 100,j=1,n1dfft
        do 100,i=n2/4+1,3*n2/4
        zw(1,j,i)=zt(1,i-n2/4,j)
        zw(2,j,i)=zt(2,i-n2/4,j)
100     continue

! High frequencies
        do 90,i=1,n2/4
        do 90,j=1,n1dfft
        zw(1,j,i)=0.d0
        zw(2,j,i)=0.d0
90      continue
        do 110,i=3*n2/4+1,n2
        do 110,j=1,n1dfft
        zw(1,j,i)=0.d0
        zw(2,j,i)=0.d0
110     continue

        return
        end