Fix slow numerical computation of zeta({7,3}).

[ginac.git] / ginac / inifcns_nstdsums.cpp

diff --git a/ginac/inifcns_nstdsums.cpp b/ginac/inifcns_nstdsums.cpp
index 0a60d780ded9f427703ee4942d8c8a2fb8510bb2..f040e8ad64df2aab86a5d8dda2d3b9c51c3e8b3d 100644 (file)
--- a/ginac/inifcns_nstdsums.cpp
+++ b/ginac/inifcns_nstdsums.cpp
@@ -3882,17 +3882,21 @@ static ex zeta1_evalf(const ex& x)
                const int count = x.nops();
                const lst& xlst = ex_to<lst>(x);
                std::vector<int> r(count);
+               std::vector<int> si(count);
 
                // check parameters and convert them
                auto it1 = xlst.begin();
                auto it2 = r.begin();
+               auto it_swrite = si.begin();
                do {
                        if (!(*it1).info(info_flags::posint)) {
                                return zeta(x).hold();
                        }
                        *it2 = ex_to<numeric>(*it1).to_int();
+                       *it_swrite = 1;
                        it1++;
                        it2++;
+                       it_swrite++;
                } while (it2 != r.end());
 
                // check for divergence
@@ -3900,6 +3904,10 @@ static ex zeta1_evalf(const ex& x)
                        return zeta(x).hold();
                }
 
+               // use Hoelder convolution if Digits is large
+               if (Digits>50)
+                       return numeric(zeta_do_Hoelder_convolution(r, si));
+
                // decide on summation algorithm
                // this is still a bit clumsy
                int limit = (Digits>17) ? 10 : 6;