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CSFFT
Routine Documentation— Input: INTEGER MODE
The value of MODE on input determines the operation performed by
CSFFT
.
On input:
- MODE=0 : only initializations (specific to the values of N) are performed using a default plan; this is usually followed by calls to the same routine with MODE=1.
- MODE=1 : a real transform is performed. Initializations are assumed to have been performed by a prior call to
CSFFT
.- MODE=2 : (default) initializations and a real transform are performed.
- MODE=100 : similar to MODE=0; only initializations (specific to the value of N) are performed, but these are based on a plan that is first generated by timing a subset of all possible plans and choosing the quickest (i.e. the FFT computation was timed as fastest based on the chosen plan). The plan generation phase may take a significant amount of time depending on the value of N.
— Input/Output: REAL X(N)
On input: X contains the Hermitian sequence of length N to be transformed.
On output: X contains the transformed real sequence.
CALL SCFFT(0,N,X,COMM,INFO) CALL SCFFT(1,N,X,COMM,INFO) DO 10 I = N/2+2, N X(I) = -X(I) 10 CONTINUE CALL CSFFT(2,N,X,COMM,INFO) |