Multithreading for nested loops

[tkf]

@Debasish

I think my matrix (RM) whose elements are being summed is being accessed by different threads inconsistently. Every time I run the program I get a different answer. This is the same problem that happens in Fortran when variables are not properly categorised into shared, private or reduction variables.

Indeed, lines like RM[i1,i1] += -GEself[1,1]/8π indicate that your code have data races. We can’t expect a deterministic behavior.

FYI, there are a couple of examples in FLoops documentation for writing reduction of mutable objects without data races. See: In-place mutation and Initialization with @reduce(acc = op(init, x)) syntax. There’s also private variables support.