Where can I see clear examples of using OpenCL?

Question

C++ / C#

I could not find an understandable manual on OpenCL on the Internet. Everywhere in the examples there are tons of lines of code that are almost not explained in any way. Where can I find clear examples of using OpenCL? (Exactly, with a detailed explanation of almost every line). If there are none, please explain how to solve such a problem using OpenCL:
let there be double[,] X, Y; equal sizes. It is necessary to write in each field Y the average value by the square 3 * 3 from X. (The numbers "beyond the edges" of X should be taken as zero.)

Answer 1

could not find a clear guide

Oh is it? But I don't think that's what you were looking for. https://www.google.com/search?sxsrf=ALeKk013a6MT8P...