[英]CuFFT Double to Complex
我想使用CuFFT Lib将FFT从double转换为std :: complex。 我的代码看起来像
#include <complex>
#include <iostream>
#include <cufft.h>
#include <cuda_runtime_api.h>
typedef std::complex<double> Complex;
using namespace std;
int main(){
int n = 100;
double* in;
Complex* out;
in = (double*) malloc(sizeof(double) * n);
out = (Complex*) malloc(sizeof(Complex) * n/2+1);
for(int i=0; i<n; i++){
in[i] = 1;
}
cufftHandle plan;
plan = cufftPlan1d(&plan, n, CUFFT_D2Z, 1);
unsigned int mem_size = sizeof(double)*n;
cufftDoubleReal *d_in;
cufftDoubleComplex *d_out;
cudaMalloc((void **)&d_in, mem_size);
cudaMalloc((void **)&d_out, mem_size);
cudaMemcpy(d_in, in, mem_size, cudaMemcpyHostToDevice);
cudaMemcpy(d_out, out, mem_size, cudaMemcpyHostToDevice);
int succes = cufftExecD2Z(plan,(cufftDoubleReal *) d_in,(cufftDoubleComplex *) d_out);
cout << succes << endl;
cudaMemcpy(out, d_out, mem_size, cudaMemcpyDeviceToHost);
for(int i=0; i<n/2; i++){
cout << "out: " << i << " " << out[i].real() << " " << out[i].imag() << endl;
}
return 0;
}
但是在我看来这一定是错误的,因为我认为转换后的值应该是1 0 0 0 0 ....或不进行归一化100 0 0 0 0 ....但我只会得到0 0 0 0 0。 ..
此外,如果cufftExecD2Z可以在适当的地方工作,我会更希望这样做,这应该是可能的,但是我还没有弄清楚如何正确地做到这一点。 有人可以帮忙吗?
您的代码有各种错误。 您可能应该查看cufft文档以及示例代码。
cufftPlan1d
函数的返回值不计入计划:
plan = cufftPlan1d(&plan, n, CUFFT_D2Z, 1);
函数本身会设置计划(这就是为什么将&plan
传递给函数的原因),然后,当您将返回值分配给计划时,它将破坏函数设置的计划。
您正确地确定输出的大小可以为((N/2)+1)
,但是在主机端您都没有为它正确分配空间:
out = (Complex*) malloc(sizeof(Complex) * n/2+1);
或在设备端:
unsigned int mem_size = sizeof(double)*n; ... cudaMalloc((void **)&d_out, mem_size);
下面的代码已修复了上述一些问题,足以得到您想要的结果(100、0、0,...)
#include <complex>
#include <iostream>
#include <cufft.h>
#include <cuda_runtime_api.h>
#define cudaCheckErrors(msg) \
do { \
cudaError_t __err = cudaGetLastError(); \
if (__err != cudaSuccess) { \
fprintf(stderr, "Fatal error: %s (%s at %s:%d)\n", \
msg, cudaGetErrorString(__err), \
__FILE__, __LINE__); \
fprintf(stderr, "*** FAILED - ABORTING\n"); \
exit(1); \
} \
} while (0)
typedef std::complex<double> Complex;
using namespace std;
int main(){
int n = 100;
double* in;
Complex* out;
#ifdef IN_PLACE
in = (double*) malloc(sizeof(Complex) * (n/2+1));
out = (Complex*)in;
#else
in = (double*) malloc(sizeof(double) * n);
out = (Complex*) malloc(sizeof(Complex) * (n/2+1));
#endif
for(int i=0; i<n; i++){
in[i] = 1;
}
cufftHandle plan;
cufftResult res = cufftPlan1d(&plan, n, CUFFT_D2Z, 1);
if (res != CUFFT_SUCCESS) {cout << "cufft plan error: " << res << endl; return 1;}
cufftDoubleReal *d_in;
cufftDoubleComplex *d_out;
unsigned int out_mem_size = (n/2 + 1)*sizeof(cufftDoubleComplex);
#ifdef IN_PLACE
unsigned int in_mem_size = out_mem_size;
cudaMalloc((void **)&d_in, in_mem_size);
d_out = (cufftDoubleComplex *)d_in;
#else
unsigned int in_mem_size = sizeof(cufftDoubleReal)*n;
cudaMalloc((void **)&d_in, in_mem_size);
cudaMalloc((void **)&d_out, out_mem_size);
#endif
cudaCheckErrors("cuda malloc fail");
cudaMemcpy(d_in, in, in_mem_size, cudaMemcpyHostToDevice);
cudaCheckErrors("cuda memcpy H2D fail");
res = cufftExecD2Z(plan,d_in, d_out);
if (res != CUFFT_SUCCESS) {cout << "cufft exec error: " << res << endl; return 1;}
cudaMemcpy(out, d_out, out_mem_size, cudaMemcpyDeviceToHost);
cudaCheckErrors("cuda memcpy D2H fail");
for(int i=0; i<n/2; i++){
cout << "out: " << i << " " << out[i].real() << " " << out[i].imag() << endl;
}
return 0;
}
查看文档,以了解在实际情况到复杂情况下进行就地转换所必需的内容。 可以使用-DIN_PLACE
重新编译以上代码,以查看就地转换的行为以及必要的代码更改。
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