unit fftun;
interface
uses Math, Sysutils, Ap, ftbase;
...
procedure FFTC1D(var A : TComplex1DArray; N : AlglibInteger);
var
Plan : FTPlan;
I : AlglibInteger;
Buf : TReal1DArray;
begin
Assert(N>0, 'FFTC1D: incorrect N!');
//
// Special case: N=1, FFT is just identity transform.
// After this block we assume that N is strictly greater than 1.
//
if N=1 then
begin
Exit;
end;
//
// convert input array to the more convinient format
//
GetMem(buf,2*n);
SetLength(Buf, 2*N);
I:=0;
while I<=N-1 do
begin
Buf[2*I+0] := A[I].X;
Buf[2*I+1] := A[I].Y;
Inc(I);
end;
//
// Generate plan and execute it.
//
// Plan is a combination of a successive factorizations of N and
// precomputed data. It is much like a FFTW plan, but is not stored
// between subroutine calls and is much simpler.
//
FTBaseGenerateComplexFFTPlan(N, Plan);
FTBaseExecutePlan(Buf, 0, N, Plan);//After this procedure, the array is filled with the Buf "+ NAN".
//
// result
//
I:=0;
while I<=N-1 do
begin
A[I].X := Buf[2*I+0];
A[I].Y := Buf[2*I+1];
Inc(I);
end;
| Attachments: |
|
after.jpg [ 37.11 KiB | Viewed 12683 times ] |
|
befor.jpg [ 25.17 KiB | Viewed 12683 times ] |