我已经编写了一个使用Intel MKL计算3D卷积的C/C++代码,数组大约有300×200×200个元素。我想应用一个大小为3×3×3或5×5×5的核。输入的3D数组和核都具有实值。
这个3D数组以列优先方式存储为double类型的1D数组。类似地,核也是double类型并以列优先方式保存。例如,
这是我的C/C++代码:
这个3D数组以列优先方式存储为double类型的1D数组。类似地,核也是double类型并以列优先方式保存。例如,
for( int k = 0; k < nk; k++ ) // Loop through the height.
for( int j = 0; j < nj; j++ ) // Loop through the rows.
for( int i = 0; i < ni; i++ ) // Loop through the columns.
{
ijk = i + ni * j + ni * nj * k;
my3Darray[ ijk ] = 1.0;
}
为了进行卷积计算,我想在输入数组和内核上执行非就地
FFT,并防止它们被修改(我需要稍后在我的代码中使用它们),然后进行就地
反向计算。
当我将我的代码得到的结果与MATLAB
得到的结果进行比较时,它们非常不同。是否有人可以帮助我解决这个问题?我的代码缺少什么?
这是我使用的MATLAB
代码:
a = ones( 10, 10, 10 );
kernel = ones( 3, 3, 3 );
aconvolved = convn( a, kernel, 'same' );
这是我的C/C++代码:
#include <stdio.h>
#include "mkl.h"
void Conv3D(
double *in, double *ker, double *out,
int nRows, int nCols, int nHeights)
{
int NI = nRows;
int NJ = nCols;
int NK = nHeights;
double *in_fft = new double [NI*NJ*NK];
double *ker_fft = new double [NI*NJ*NK];
DFTI_DESCRIPTOR_HANDLE fft_desc = 0;
MKL_LONG sizes[] = { NK, NJ, NI };
MKL_LONG strides[] = { 0, NJ*NI, NI, 1 };
DftiCreateDescriptor( &fft_desc, DFTI_DOUBLE, DFTI_REAL, 3, sizes );
DftiSetValue ( fft_desc, DFTI_PLACEMENT , DFTI_NOT_INPLACE); // Out-of-place computation.
DftiSetValue ( fft_desc, DFTI_INPUT_STRIDES , strides );
DftiSetValue ( fft_desc, DFTI_OUTPUT_STRIDES, strides );
DftiSetValue ( fft_desc, DFTI_BACKWARD_SCALE, 1/NI/NJ/NK );
DftiCommitDescriptor( fft_desc );
DftiComputeForward ( fft_desc, in , in_fft );
DftiComputeForward ( fft_desc, ker, ker_fft );
for (long long i = 0; i < (long long)NI*NJ*NK; ++i )
out[i] = in_fft[i]*ker_fft[i];
// In-place computation.
DftiSetValue ( fft_desc, DFTI_PLACEMENT, DFTI_INPLACE );
DftiCommitDescriptor( fft_desc );
DftiComputeBackward ( fft_desc, out );
DftiFreeDescriptor ( &fft_desc );
delete[] in_fft;
delete[] ker_fft;
}
int main(int argc, char* argv[])
{
int n = 10;
int nkernel = 3;
double *a = new double [n*n*n]; // This array is real.
double *aconvolved = new double [n*n*n]; // The convolved array is also real.
double *kernel = new double [nkernel*nkernel*nkernel]; // kernel is real.
// Fill the array with some 'real' numbers.
for( int i = 0; i < n*n*n; i++ )
a[ i ] = 1.0;
// Fill the kernel with some 'real' numbers.
for( int i = 0; i < nkernel*nkernel*nkernel; i++ )
kernel[ i ] = 1.0;
// Calculate the convolution.
Conv3D( a, kernel, aconvolved, n, n, n );
printf("Convolved:\n");
for( int i = 0; i < n*n*n; i++ )
printf( "%15.8f\n", aconvolved[i] );
delete[] a;
delete[] kernel;
delete[] aconvolved;
return 0;
}