vector_projection.cu

#include <stdio.h>

#include "helper_cuda.h"
#include <cuda_runtime.h>

template<typename T> __global__ void vector_projection(T *dx, int n) {
    int tid;
    tid = threadIdx.x + blockIdx.x * blockDim.x;
    if (tid < n) {
        if (dx[tid] < 0)
            dx[tid] = (T) 0;
    }
}

double X[10] = {1,-2,3,-4,5,-6,7,-8,9,-10};


int main(void) {
    int i;

    double *dev_X;
    checkCudaErrors(cudaMalloc(&dev_X, 10*sizeof(double)));
    checkCudaErrors(cudaMemcpy(dev_X, X, 10*sizeof(double), cudaMemcpyHostToDevice));

    vector_projection<double><<<1,10>>>(dev_X, 10);
    getLastCudaError("vector_projection");

    checkCudaErrors(cudaMemcpy(X, dev_X, 10*sizeof(double), cudaMemcpyDeviceToHost));
    for (i=0; i<10; i++)
    {
        printf("proj(X) = %g\n", i, X[i]);
    }

    return 0;
}