I can confirm that I was able to successfully compile and run my test code with this patch applied. took about 10 seconds to execute. Thanks for the help guys peter Quoting Alexei Sheplyakov <alexei.sheplyakov@gmail.com>:
The patch below (drastically) improves the run time at the expense of using more RAM in some situations. Please note: it doesn't improve the actual algorithm (iteration over all permutations).
diff --git a/ginac/symmetry.cpp b/ginac/symmetry.cpp index 7d1ff97..d93e34c 100644 --- a/ginac/symmetry.cpp +++ b/ginac/symmetry.cpp @@ -22,6 +22,7 @@
#include "symmetry.h" #include "lst.h" +#include "add.h" #include "numeric.h" // for factorial() #include "operators.h" #include "archive.h" @@ -495,7 +496,8 @@ static ex symm(const ex & e, exvector::const_iterator first, exvector::const_ite
// Loop over all permutations (the first permutation, which is the // identity, is unrolled) - ex sum = e; + exvector sum_v; + sum_v.push_back(e); while (std::next_permutation(iv, iv + num)) { lst new_lst; for (unsigned i=0; i<num; i++) @@ -505,8 +507,9 @@ static ex symm(const ex & e, exvector::const_iterator first, exvector::const_ite memcpy(iv2, iv, num * sizeof(unsigned)); term *= permutation_sign(iv2, iv2 + num); } - sum += term; + sum_v.push_back(term); } + ex sum = (new add(sum_v))->setflag(status_flags::dynallocated);
delete[] iv; delete[] iv2;
Best regards, Alexei
P.S. The bug has nothing to do with infinite loops.
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