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DZFFTM Routine Documentation
— SUBROUTINE: DZFFTM (M,N,X,COMM,INFO)
— Input: INTEGER M

On input: M is the number of sequences to be transformed.

— Input: INTEGER N

On input: N is the length of the real sequences in X

— Input/Output: DOUBLE PRECISION X(N*M)

On input: X contains the M real sequences of length N to be transformed. Element i of sequence j is stored in location i+(j-1)*N of X.
On output: X contains the transformed Hermitian sequences.

— Input/Output: DOUBLE PRECISION COMM(3*N+100)

COMM is a communication array. Some portions of the array are used to store initializations for subsequent calls with the same sequence length N. The remainder is used as temporary store.

— Output: INTEGER INFO

On output: INFO is an error indicator. On successful exit, INFO contains 0. If INFO = -i on exit, the i-th argument had an illegal value.

Example: 

             CALL DZFFTM(1,N,X,COMM,INFO)
             CALL DZFFTM(2,N,X,COMM,INFO)
             DO 10 I = 1, N
                X(I,3) = X(I,1)*X(N-I+1,2)
        10   CONTINUE
             CALL ZDFFTM(2,N,X(1,3),COMM,INFO)