Re: [Boost-users] bracket_and_solve_root "rising" option

-----Original Message----- From: Boost-users On Behalf Of Saurabh T via Boost-users Sent: 7 November 2019 12:51 To: boost-users@lists.boost.org Cc: Saurabh T Subject: [Boost-users] bracket_and_solve_root "rising" option

Hi,

I would like a way to bracket the root without having to compute or specify the "rising" flag to "bracket_and_solve_root". Is there a way to edit the bracketing implementation so the user need not specify that option? Thanks,

You could just assume is_rising ==true and see if it converges by testing if iterations >= max_iterations Setting max_iterations to a sensible value (<50) will avoid a long wait 😉 If it doesn't converge, try is_rising = false. Crude and slow? Or you could compute the bounds yourself and use TOMS748 boost/libs/math/doc/html/math_toolkit/roots_noderiv/TOMS748.html but that means more work. Or you could use Brent's algorithm \math\example\brent_minimise_example.cpp, but you still need to provide bracket values, and choosing -infinity and +infinity will not be fast. (Again limiting the number of iterations is wise if you fear a long wait). Fundamentally it is important to provide the algorithm with as much info as possible as a guess, bracket limits, and is rising or falling in order that it works efficiently, or indeed at all. I suspect you do know more really? HTH Paul