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[英]How to efficiently extract real/imaginary parts of complex matrix in Eigen3 library?
[英]How to get the real and imaginary parts of a complex matrix separately in CUDA?
我正試圖獲得2D陣列的fft。 輸入是NxM
實矩陣,因此輸出矩陣也是NxM
矩陣( 2xNxM
輸出矩陣使用厄米特對稱性保存在NxM矩陣中)。
所以我想知道是否有方法在cuda中提取以分別提取實數和復數矩陣? 在opencv中分割功能是有責任的。 所以我在尋找cuda中的類似功能,但我還沒找到它。
以下是我的完整代碼
#define NRANK 2
#define BATCH 10
#include "cuda_runtime.h"
#include "device_launch_parameters.h"
#include <cufft.h>
#include <stdio.h>
#include <iostream>
#include <vector>
using namespace std;
int main()
{
const size_t NX = 4;
const size_t NY = 5;
// Input array - host side
float b[NX][NY] ={
{0.7943 , 0.6020 , 0.7482 , 0.9133 , 0.9961},
{0.3112 , 0.2630 , 0.4505 , 0.1524 , 0.0782},
{0.5285 , 0.6541 , 0.0838 , 0.8258 , 0.4427},
{0.1656 , 0.6892 , 0.2290 , 0.5383 , 0.1067}
};
// Output array - host side
float c[NX][NY] = { 0 };
cufftHandle plan;
cufftComplex *data; // Holds both the input and the output - device side
int n[NRANK] = {NX, NY};
// Allocated memory and copy from host to device
cudaMalloc((void**)&data, sizeof(cufftComplex)*NX*(NY/2+1));
for(int i=0; i<NX; ++i){
// Uses this because my actual array is a dynamically allocated.
// but here I've replaced it with a static 2D array to make it simple.
cudaMemcpy(reinterpret_cast<float*>(data) + i*NY, b[i], sizeof(float)*NY, cudaMemcpyHostToDevice);
}
// Performe the fft
cufftPlanMany(&plan, NRANK, n,NULL, 1, 0,NULL, 1, 0,CUFFT_R2C,BATCH);
cufftSetCompatibilityMode(plan, CUFFT_COMPATIBILITY_NATIVE);
cufftExecR2C(plan, (cufftReal*)data, data);
cudaThreadSynchronize();
cudaMemcpy(c, data, sizeof(float)*NX*NY, cudaMemcpyDeviceToHost);
// Here c is a NxM matrix. I want to split it to 2 seperate NxM matrices with each
// having the complex and real component of the output
// Here c is in
cufftDestroy(plan);
cudaFree(data);
return 0;
}
正如JackOLanter所建議的,我修改了如下代碼。 但問題仍然沒有解決。
float real_vec[NX][NY] = {0}; // host vector, real part
float imag_vec[NX][NY] = {0}; // host vector, imaginary part
cudaError cudaStat1 = cudaMemcpy2D (real_vec, sizeof(real_vec[0]), data, sizeof(data[0]),NY*sizeof(float2), NX, cudaMemcpyDeviceToHost);
cudaError cudaStat2 = cudaMemcpy2D (imag_vec, sizeof(imag_vec[0]),data + 1, sizeof(data[0]),NY*sizeof(float2), NX, cudaMemcpyDeviceToHost);
我得到的錯誤是'無效音高參數錯誤'。 但我無法理解為什么。 對於目的地,我使用間距大小為'float',而對於源我使用'float2'的大小
你的問題和你的代碼對我來說沒有多大意義。
cufftExecR2C
的輸出是NX*(NY/2+1)
float2
矩陣,可以解釋為NX*(NY+2)
float
矩陣。 因此,您沒有為最后一個cudaMemcpy
為c
(僅為NX*NY
float
)分配足夠的空間。 對於輸出的連續組件,您仍然需要一個復雜的內存位置; cufftExecR2C
命令cufftExecR2C
,但更為通用:如何將復雜的NX*NY
矩陣分別分為包含實部和虛部的2
NX*NY
實矩陣。 如果我正確地解釋了你的問題,那么@njuffa提出的解決方案就是
可能是你的一個很好的線索。
編輯
下面是一個小例子,說明當復制矢量從/向主機復制到設備時,如何“組裝”和“拆解”復數矢量的實部和虛部。 請添加您自己的CUDA錯誤檢查 。
#include <stdio.h>
#define N 16
int main() {
// Declaring, allocating and initializing a complex host vector
float2* b = (float2*)malloc(N*sizeof(float2));
printf("ORIGINAL DATA\n");
for (int i=0; i<N; i++) {
b[i].x = (float)i;
b[i].y = 2.f*(float)i;
printf("%f %f\n",b[i].x,b[i].y);
}
printf("\n\n");
// Declaring and allocating a complex device vector
float2 *data; cudaMalloc((void**)&data, sizeof(float2)*N);
// Copying the complex host vector to device
cudaMemcpy(data, b, N*sizeof(float2), cudaMemcpyHostToDevice);
// Declaring and allocating space on the host for the real and imaginary parts of the complex vector
float* cr = (float*)malloc(N*sizeof(float));
float* ci = (float*)malloc(N*sizeof(float));
/*******************************************************************/
/* DISASSEMBLING THE COMPLEX DATA WHEN COPYING FROM DEVICE TO HOST */
/*******************************************************************/
float* tmp_d = (float*)data;
cudaMemcpy2D(cr, sizeof(float), tmp_d, 2*sizeof(float), sizeof(float), N, cudaMemcpyDeviceToHost);
cudaMemcpy2D(ci, sizeof(float), tmp_d+1, 2*sizeof(float), sizeof(float), N, cudaMemcpyDeviceToHost);
printf("DISASSEMBLED REAL AND IMAGINARY PARTS\n");
for (int i=0; i<N; i++)
printf("cr[%i] = %f; ci[%i] = %f\n",i,cr[i],i,ci[i]);
printf("\n\n");
/******************************************************************************/
/* REASSEMBLING THE REAL AND IMAGINARY PARTS WHEN COPYING FROM HOST TO DEVICE */
/******************************************************************************/
cudaMemcpy2D(tmp_d, 2*sizeof(float), cr, sizeof(float), sizeof(float), N, cudaMemcpyHostToDevice);
cudaMemcpy2D(tmp_d + 1, 2*sizeof(float), ci, sizeof(float), sizeof(float), N, cudaMemcpyHostToDevice);
// Copying the complex device vector to host
cudaMemcpy(b, data, N*sizeof(float2), cudaMemcpyHostToDevice);
printf("REASSEMBLED DATA\n");
for (int i=0; i<N; i++)
printf("%f %f\n",b[i].x,b[i].y);
printf("\n\n");
getchar();
return 0;
}
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