I am testing the FFT routines in MKL library. Following the example code, I was able to do 1D forward FFT for an array input supplied by a text file. Then a backward FFT is performed and the result is saved in another text file.
Theoretically, the output of the backward FFT should be the same as the input array. But what I get is not. The real part is scaled by n (number of points) and the imaginary part is pure zero.
The attached files are the code, input file and output file. Please help me through. Thanks.