I've discovered that that the results are the same with GNU libstdc++ as with Dinkumware. But I belive they both bring in the math functions from libm.so.2.
Anyhow, I'm stumped by what the issue could be now, so can you let me have the output of the program below?
Here it is: .../ellint_1.hpp:48 phi = -10 .../ellint_1.hpp:49 k = 0.5 .../ellint_1.hpp:50 function = boost::math::ellint_f<%1%>(%1%,%1%) .../ellint_1.hpp:61 phi = -10 .../ellint_1.hpp:90 pi/2 = 1.57079632679489661937 .../ellint_1.hpp:92 rphi = 0.57522203923062028381 .../ellint_1.hpp:94 m = 5.99999999999999999964 .../ellint_1.hpp:101 rphi = 0.99557428756427633551 .../ellint_1.hpp:105 sinp = 0.83907152907645245276 .../ellint_1.hpp:106 cosp = 0.5440211108893698126 .../ellint_rf.hpp:67 tolerance = 0.000870018279433925102139 .../ellint_rf.hpp:96 k = 6 .../ellint_rf.hpp:102 value = 1.23050187733714060618 .../ellint_1.hpp:108 result = -1.03247909174871990352 .../ellint_rf.hpp:67 tolerance = 0.000870018279433925102139 .../ellint_rf.hpp:96 k = 7 .../ellint_rf.hpp:102 value = 1.68575035481259604281 .../ellint_1.hpp:112 result = 10.76777339193945239443 -10.76777339193945239443 I cut off most of the path in the output. The output is the same with either library.