A noob need help

A noob need help

global void square_array(float *a, int N)
{
int idx = blockIdx.x * blockDim.x + threadIdx.x;
if (idx<N) a[idx] = a[idx] * a[idx];
}

square_array <<< 3, 4 >>> (a_d, N);

I need help for this code segment:

int idx = blockIdx.x * blockDim.x + threadIdx.x;
if (idx<N) a[idx] = a[idx] * a[idx];

N = 10

Can you explain the two codelines for me.

This line is defining the thread’s position within the grid. It is used to access memory in vector format as shown in the next line:

As the grid consists of 12 threads, and you only want to consider the first 10, a conditional statement is used based on the thread’s position within the grid.

Hope that makes sense…