%N fftcr %F $MIR/src/subs/fftsubs.for
%D Complex to real 1D FFT routine.
%: fourier-transform, fft
%P rjs
%B
        subroutine fftcr(in,out,isn,n)

        integer n,isn
        real in(n+2),out(n)

  This performs a 1D Fourier transform of a complex sequence (with
  conjugate symmetry), to produce a real output. There is no
  1/N scaling, and the "phase center" of the transform is the first
  element of the input array.

  Input:
    in         The input complex array.  Will normally be dimensioned
               as N/2+1 complex elements.  Because the sequence is
               assumed to have conjugate symmetry, only half the input
               array is needed.  The first element corresponds to the
               "DC" term.  This array could also be declared to be a
               real array of size N+2 elements.
    isn        The sign of the exponent in the transform, This can be
               either 1 or -1.
    n          The number of elements to transform.  Must be a power
               of 2.
  Output:
    out        The output real array.
