Thanks for replying. Will ask here if I have any further questions.
On Wed, Jan 27, 2021 at 6:38 PM John Maddock via Boost-users <boost-users@lists.boost.org> wrote: > > On 26/01/2021 15:46, Shriramana Sharma via Boost-users wrote: > > Namaste. > > > > This is wrt the TOMS748 math root finding implementation: > > > > Given that `if(fa == 0)` is handled at: > > > > https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms748_solve.hpp#L325 > > > > … and the function returns in case of the above condition, it is not > > clear to me what the need is for the `if (fa != 0)` at: > > > > https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms748_solve.hpp#L342 > > You're quite right - it's superfluous, will fix. > > > Now I also note similar checks at: > > > > https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms748_solve.hpp#L352 > > https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms748_solve.hpp#L366 > > > > … but regarding those lines, while I can understand the need for > > checking there after more bracketing work is done, it is not clear to > > me why `(fa == 0)` is alone checked for, and not `(fb == 0)` as well. > > I would have thought the algorithm is not biased towards a or b. > > When bracket() is called, it updates either fa or fb with the next value > (fc), and when fc is zero then fa is always set to zero, and the result > is always a. So checking fb == 0 is unnecessary after a bracket() call. > > > Indeed, in the last steps from: > > > > https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms748_solve.hpp#L465, > > > > … both the conditions are checked for, > > Somewhat different situation - at this point the loop has terminated, > and we're just tightening up our interval in the case that one of a or b > is right on the root. This is a nicety not required by the algorithm as > such, and indeed the fb == 0 branch *may* be superfluous, but I would > want to think very carefully indeed before changing it ;) > > Best, John Maddock. > > -- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > _______________________________________________ > Boost-users mailing list > Boost-users@lists.boost.org > https://lists.boost.org/mailman/listinfo.cgi/boost-users -- Shriramana Sharma ஶ்ரீரமணஶர்மா श्रीरमणशर्मा 𑀰𑁆𑀭𑀻𑀭𑀫𑀡𑀰𑀭𑁆𑀫𑀸 _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org https://lists.boost.org/mailman/listinfo.cgi/boost-users
