Matrix multiplication issue

I need to multiply 2 square matrices (1024*1024). This following program is written by myself, I believe I am getting the correct output after the multiplication. Once compiled using the command “make emu=1”(Using NVIDIA SDK) I am getting a warning as “./matrixMulNew_kernel.cu(60): warning: expression has no effect”, here line no 60 begins with,

for(p=0,q=N-1; p<N, q>=0; ++p, q–){

sum = sum + a[p+(j*N)] * b[i+(q*N)];

}

Please go through my Kernel prog and let me know why I am getting the above warning. :rolleyes:

N= 1024

blocksize = 16;

===Kernel Program===

**global** void mul_matrix ( float* a, float* b, float* c, int N ) {

int i = blockIdx.x * blockDim.x + threadIdx.x;

int j = blockIdx.y * blockDim.y + threadIdx.y;

int index = i + j*N;
float sum = 0;
int p,q;
for(p=0,q=N-1; p<N, q>=0; ++p, q–){
sum = sum + a[p+(j*N)] * b[i+(q*N)];

}

c[index] = sum;

}

===Kernel invocation code===

dim3 dimBlock( blocksize, blocksize );

dim3 dimGrid( N/dimBlock.x, N/dimBlock.y );

mul_matrix<<<dimGrid, dimBlock>>>( ad, bd, cd, N );

Here one thread is responsible for calculating a single value in matrix C