寻找cuda中n个点之间的最小距离

I am trying to find the minimum distance between n points in cuda. I wrote the below code. This is working fine for number of points from 1 to 1024 i.e., 1 block. But if num_points is greater than 1024 i am getting wrong value for minimum distance. I am checking the gpu min value with the value I found in CPU using brute force algorithm. The min value is stored in the temp1[0] at the end of kernel function.I am trying to find the minimum distance betwee