fftsg.f

来自「2维fft程序」· F 代码 · 共 2,173 行 · 第 1/5 页

                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 + nm
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 - 2 * nm
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
              end do
              k1 = 4 * k + 2 * ip(m + k)
              j1 = k1 + 2
              k1 = k1 + nh
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 + nm
              k1 = k1 + 2 * nm
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 + nm
              k1 = k1 - nm
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 - 2
              k1 = k1 - nh
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 + nh + 2
              k1 = k1 + nh + 2
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 - nh + nm
              k1 = k1 + 2 * nm - 2
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
          end do
      else
          do k = 0, m - 1
              do j = 0, k - 1
                  j1 = 4 * j + ip(m + k)
                  k1 = 4 * k + ip(m + j)
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 + nm
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nh
                  k1 = k1 + 2
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 - nm
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + 2
                  k1 = k1 + nh
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 + nm
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nh
                  k1 = k1 - 2
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 - nm
                  xr = a(j1)
                  xi = a(j1 + 1)
                  yr = a(k1)
                  yi = a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
              end do
              k1 = 4 * k + ip(m + k)
              j1 = k1 + 2
              k1 = k1 + nh
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 + nm
              k1 = k1 + nm
              xr = a(j1)
              xi = a(j1 + 1)
              yr = a(k1)
              yi = a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
          end do
      end if
      end
!
      subroutine bitrv2conj(n, ip, a)
      integer n, ip(0 : *), j, j1, k, k1, l, m, nh, nm
      real*8 a(0 : n - 1), xr, xi, yr, yi
      m = 1
      l = n / 4
      do while (l .gt. 8)
          m = m * 2
          l = l / 4
      end do
      nh = n / 2
      nm = 4 * m
      if (l .eq. 8) then
          do k = 0, m - 1
              do j = 0, k - 1
                  j1 = 4 * j + 2 * ip(m + k)
                  k1 = 4 * k + 2 * ip(m + j)
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 + 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 - nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 + 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nh
                  k1 = k1 + 2
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 - 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 + nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 - 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + 2
                  k1 = k1 + nh
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 + 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 - nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 + nm
                  k1 = k1 + 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nh
                  k1 = k1 - 2
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 - 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 + nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
                  j1 = j1 - nm
                  k1 = k1 - 2 * nm
                  xr = a(j1)
                  xi = -a(j1 + 1)
                  yr = a(k1)
                  yi = -a(k1 + 1)
                  a(j1) = yr
                  a(j1 + 1) = yi
                  a(k1) = xr
                  a(k1 + 1) = xi
              end do
              k1 = 4 * k + 2 * ip(m + k)
              j1 = k1 + 2
              k1 = k1 + nh
              a(j1 - 1) = -a(j1 - 1)
              xr = a(j1)
              xi = -a(j1 + 1)
              yr = a(k1)
              yi = -a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              a(k1 + 3) = -a(k1 + 3)
              j1 = j1 + nm
              k1 = k1 + 2 * nm
              xr = a(j1)
              xi = -a(j1 + 1)
              yr = a(k1)
              yi = -a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 + nm
              k1 = k1 - nm
              xr = a(j1)
              xi = -a(j1 + 1)
              yr = a(k1)
              yi = -a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 - 2
              k1 = k1 - nh
              xr = a(j1)
              xi = -a(j1 + 1)
              yr = a(k1)
              yi = -a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 + nh + 2
              k1 = k1 + nh + 2
              xr = a(j1)
              xi = -a(j1 + 1)
              yr = a(k1)
              yi = -a(k1 + 1)
              a(j1) = yr
              a(j1 + 1) = yi
              a(k1) = xr
              a(k1 + 1) = xi
              j1 = j1 - nh + nm
              k1 = k1 + 2 * nm - 2
              a(j1 - 1) = -a(j1 - 1)
              xr = a(j1)
              xi = -a(j1 + 1)
              yr = a(k1)
              yi = -a(k1 + 1)
              a(j1) = yr