fftw_loop.cpp

Output

Armadillo FFT Time = 46.8176
FFTW Loop[1]. Time = 0.052592
FFTW Loop[2]. Time = 0.003976
FFTW Loop[3]. Time = 0.003865
FFTW Loop[4]. Time = 0.003716

Source

 
#include "sigpack.h"
using namespace arma;
 
int main()
{
    int      N = 45191; // Large prime number
    sp::FFTW ss( N, FFTW_ESTIMATE );
    vec      x( N );
    cx_vec   Sxx( N );
 
    vec     P( N );
    clock_t tic;
    x.randn();
    tic = clock();
    Sxx = fft( x );
    cout << "Armadillo FFT Time = " << ( clock() - tic ) / double( CLOCKS_PER_SEC ) << endl;
 
    tic = clock();
    Sxx = fft( x );
    cout << "Armadillo FFT Time = " << ( clock() - tic ) / double( CLOCKS_PER_SEC ) << endl;
 
    for( int n = 1; n < 5; n++ )
    {
        x.randn();
        tic = clock();
        Sxx = ss.fft( x );
        cout << "FFTW Loop[" << n << "]. Time = " << ( clock() - tic ) / double( CLOCKS_PER_SEC ) << endl;
    }
    return 0;
}