How to do that with multi-processing

[Assaf David Hillel]

Hii
I try to understand how to do it parallel,
do you have any idea?

[kburfi]

The trilateration itself is done by the Levenberg–Marquardt algorithm, which is a standard implementation. So calculating the result for a single problem in parallel is not simple and would lead you to implementing a new algorithm. Hence this is way out of scope.
You could of course just run the trilateration with multiple positions in parallel. E. g. using different threads or parllel streams..