Hi. I need to filter some signal, but I am stuck. Array with “in” samples is going good through GPU, also is array with coefficients of filter “MassFilter”. But “out” is filled by zeros. I have a low pass filter, so result is depend on Fotn. If Fotn > then bandpass frequency - the result is either as “in”, if <, the result is going to be near zeros. Bandpass freq = 250, stopband freq = 400.

Help please, what am I doing wrong? Thanks.

```
#include <iostream>
#include <cuda.h>
#include <cmath>
#include <fstream>
#define M_PI 3.14159
#define SizeSample 1000
#define SizeFilter 10
#define Fotn 0.1
double Fd = 1000;
double in;
double out;
__global__ void mult(double* in, double* out, double* MassFilter1, int SizeFilter1, int SizeSample1)
{
double sum = 0.0f;
int idx = blockIdx.x * blockDim.x + threadIdx.x;
__shared__ double as [1024];
as[threadIdx.x]=in[idx];
as=in;
__syncthreads();
//sum=0.0f;
for(int i=0;i<SizeFilter1;i++)
{
sum+=as[threadIdx.x+i]*MassFilter1[i];
}
out=sum;
}
int main()
{
int dataLength = 1000;
double *h_data = new double[1000];
double *h_filteredData = new double;
double *h_filter = new double;
double A=-1.0;
double B=1.0;
double Amp = ((double)A + rand() / ((B + 1) - A));
for(int i = 0; i < 1000; i++)
{
in[i] = Amp * sinf(2 * M_PI * Fotn * i);
}
double MassFilter = {0.0150682406405476188, 0.0631055096724139019, -0.107340878395980121, 0.0151929408492773276,
0.495319687127840069, 0.495319687127840069, 0.0151929408492773276, -0.107340878395980121, 0.0631055096724139019, 0.0150682406405476188};
cudaMemcpy(in, h_data, dataLength* sizeof(double), cudaMemcpyHostToDevice);
cudaMemcpy(MassFilter, h_filter, SizeFilter * sizeof(double), cudaMemcpyHostToDevice);
dim3 threads (SizeFilter);
dim3 blocks (SizeSample/threads.x );
mult<<<blocks, threads>>>(in, out, MassFilter, SizeFilter, SizeSample);
cudaMemcpy(h_filteredData, out, SizeSample * sizeof(double), cudaMemcpyDeviceToHost);
for(int i = 0; i < 1000; i++)
{
printf("%d \n", out[i]);
}
delete [] h_data;
delete [] h_filteredData;
delete [] h_filter;
return 0;
}
```