Typically you generate 4 partial sums in your loop and then just sum horizontally across the 4 elements after the loop, e.g. #include <cassert> #include <cstdint> #include <emmintrin.h> float vsum(const float *a, int n) { float sum; __m128 vsum = _mm_set1_ps(0.0f); assert((n & 3) == 0); assert(((uintptr_t)a & 15) == 0); for (int i = … Read more
Dithering Well I got some time for this today so here the result. You did not provide your plotter color palette so I extracted it from your resulting images but you can use any. The idea behind dithering is simple our perception integrates color on area not individual pixels so you have to use some … Read more
Yes it is possible to do an array reduction with OpenMP. In Fortran it even has construct for this. In C/C++ you have to do it yourself. Here are two ways to do it. The first method makes private version of S for each thread, fill them in parallel, and then merges them into S … Read more