Dear all,
I have encountered a problem while using Boost C++ libraries (
multiprecision/mpc.hpp, math/quadrature) which I cannot resolve.
This problems appears when running the following piece of code
||
|#include #include
#include
#include
#include namespace mpns =
boost::multiprecision; typedef
mpns::number > mpc_type
; typedef mpc_type::value_type mp_type ; int main() { using
boost::math::constants::root_pi ; mpc_type z{mp_type(1),mp_type(1)} ;
auto f = [&](mp_type x) { //actually I did not test if all these
conditions are needed... if (boost::math::fpclassify (x) ==
FP_ZERO) { return mpc_type(mp_type(1)) ; }; if
(boost::math::fpclassify (x) == FP_INFINITE) { return
mpc_type(mp_type(0)) ; }; mp_type x2 = mpns::pow(x,2U) ; if
(boost::math::fpclassify (x2) == FP_ZERO) { return
mpc_type(mp_type(1)) ; }; if (boost::math::fpclassify (x2) ==
FP_INFINITE) { return mpc_type(mp_type(0)) ; }; mpc_type ex2 =
mpns::exp(-z*x2) ; if (boost::math::fpclassify (ex2) ==
FP_ZERO) { return mpc_type(mp_type(0)) ; }; return ex2 ; } ; mp_type
termination = boost::math::tools::root_epsilon () ; mp_type
error; mp_type L1; size_t max_halvings = 12;
boost::math::quadrature::exp_sinh integrator(max_halvings) ;
mpc_type res = integrator.integrate(f,termination,&error,&L1) ; mpc_type
div = 2U*mpns::sqrt(z) ; mpc_type result = (mpc_type(root_pi
())/div) - res ; return 0; } |
||Namely, the problem appears when evaluating the exponent.
The code is compiled without any problems, but hangs on computing
| mpc_type ex2 = mpns::exp(-z*x2) ;|
It was possible to go into the function while debugging.
It crashed eventually, when the compiler reached "unable to resolve
non-existing file.../src/init2.c".
I let it run for a while checking the call stack. It appears that the
programs is stuck atcalling ___gmpn_sub_n_coreisbr().
Or better, in the call stuck it appeared frequently.
I did several tests.
The real-valued version (with mpfr_backend <2000>) works without any
problems.
cpp_complex_backend <100> works fine, but I could not test higher
precision yet, since it is much slower.
I found a work-around which is not ideal. Namely,
mpc_type ex2 = mpc_type(mpns::exp(x2)) ;
mpc_type ezx2 = mpns::pow(ex2,-z) ;
works fine with mpc_complex_backend <2000>.
The lambda-function as it is declared in the code above works and yields
correct numbers.
The problem appears when it is called from the integrator.
My system.
I use openSUSE Tumbeleweed.
I installed boost libraries as provided by
|boost_1_76_0-gnu-mpich-hpc-devel.|
Complier -> g++, cppStandard gnu+17.
I check that I have all libs, e.g. libgmp, libmpc, libmpfr and etc.
All headers are present (the programs is complied without any warnings).
Thank you in advance and
Best wishes,
Kirill
||
