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POCUDA 2D array nvidia
 

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  1. POCUDA 2D array nvidia
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    <p>I am using <code>cudaMallocPitch</code> and <code>cudaMemcpy2D</code> for 2D array. I am not sure that I have coded correct even though I could not get the output correctly. Can any one help please? Can any one debug my error? Thanks in advance. </p> <pre><code>#include&lt;stdio.h&gt; #include&lt;cuda.h&gt; #define siz 4*sizeof(int) __global__ void addmatrix(int *m1,int *m2,size_t pitch) { int r=threadIdx.x; int *r1=m1+r*pitch; int *r2=m2+r*pitch; int c; for(c=1;c&lt;=4;c++) { r1[c]+=r2[c]; } } int main() { int i,j; int **m1_c,**m2_c; int *m1_d,*m2_d; size_t pitch; cudaError_t err; m1_c=(int **)malloc(4*sizeof(int *)); for(i=1;i&lt;=4;i++) { m1_c[i]=(int *)malloc(siz); } m2_c=(int **)malloc(4*sizeof(int *)); for(i=1;i&lt;=4;i++) { m2_c[i]=(int *)malloc(siz); } for(i=1;i&lt;=4;i++) { for(j=1;j&lt;=4;j++) { m1_c[i][j]=rand()%10; m2_c[i][j]=rand()%10; } } for(i=1;i&lt;=4;i++) { for(j=1;j&lt;=4;j++) { printf("%d\t",m1_c[i][j]); } printf("\n"); } printf("\n\n"); for(i=1;i&lt;=4;i++) { for(j=1;j&lt;=4;j++) { printf("%d\t",m2_c[i][j]); } printf("\n"); } err=cudaMallocPitch((void **)&amp;m1_d,&amp;pitch,siz,siz); err=cudaMallocPitch((void **)&amp;m2_d,&amp;pitch,siz,siz); err=cudaMemcpy2D(m1_d,pitch,m1_c,siz,siz,4,cudaMemcpyHostToDevice); err=cudaMemcpy2D(m2_d,pitch,m2_c,siz,siz,4,cudaMemcpyHostToDevice); dim3 grid(1); dim3 block(16); addmatrix&lt;&lt;&lt;grid,block&gt;&gt;&gt;(m1_d,m2_d,siz); cudaMemcpy2D(m1_c,siz,m1_d,pitch,siz,4,cudaMemcpyDeviceToHost); for(i=1;i&lt;=4;i++) { for(j=1;j&lt;=4;j++) { printf("%d\t",m1_c[i][j]); } printf("\n"); } err=cudaFree(m1_d); err=cudaFree(m2_d); err=cudaDeviceReset(); } </code></pre>
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    1. USTomasz Dzięcielewski
    1. USdambigan
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    1. COCan you include the error that you are getting?
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      1. USRen
    2. COIf you want help with your problem, you are going to have to provide a far better description of your problem. "could not get the output correctly" is not nearly enough information to help you. What, exactly, happens? What do you think should happen? Why are you not checking the return values of each CUDA API function? What CUDA version, GPU and operating system are you using? These are the sorts of things someone will need to know good answers to before they can answer your question
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      1. UStalonmies
    3. COThere are at least 2 problems with your code. You cannot pass a pointer to a 2D array to cudaMemcpy2D. You should read about [what it does](http://docs.nvidia.com/cuda/cuda-runtime-api/index.html#group__CUDART__MEMORY_1g17f3a55e8c9aef5f90b67cdf22851375) and the types of parameters it expects. For cudaMemcpy2D, both pointers are pointers to memory, but you are passing one pointer to memory and one pointer to a pointer to memory. The second problem is that all of your array indexing is starting at 1 instead of 0. Perhaps you don't understand the basics of C array indexing.
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      1. USRobert Crovella
 

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