Hello Mr. Klöckner,

I work with your PyOpenCL Package for my own PhD at TU-Darmstadt in the field of applied mathematics. It is great! Thank you for your effords!


Right know I try to handle a problem, and my google-Research did not work out. I do some calculations of Voronoi-Cells (nearest neighbor-problem). Therefore, I write into my Result array, which is quite big (Number of Points > 250.000).

I only want to store True/False to keep the information of closest neighbors. (i.e. Pnt 12 is Neighbour of Pnt 13 => 12/13 = 1)

I compressed this information to a uint8 linear array (Values 0-255) and I do bit manipulations to store 8 Neighbor Informations.

Furthermore the array grows with the Gaussian sum:


        0       1       2       3


1       0

2       0       1

3       0       1       0




nachbar  = zeros(array_size, dtype=uint8)

nachbar_buf = cl.Buffer(ctx, mf.READ_WRITE | mf.USE_HOST_PTR, hostbuf=nachbar)


int index = (cur_compare_pnt-1)*cur_compare_pnt/2 + cur_pnt;

int main_index = index / 8;

int sub_index = index % 8;


nachbar_buf[main_index] |= 1<<sub_index;


I am not sure, if this was understandable… I hope so. My problem is, that this process is not vectorizable, since I write with different Point Tupels into the same uint8 Entry.

My question is: Is there a way to use a bool-linear- array in OpenCL? Or is there a better way at all?


Thank you very much. I started with OpenCL at all one year ago and your work help a lot.