
Boost Users : 
From: Shriramana Sharma (samjnaa_at_[hidden])
Date: 20210126 15:46:15
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
â€¦ 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
Note that I do not find the condition being applied at the SciPy
implementation of this algorithm at:
https://github.com/scipy/scipy/blob/v1.6.0/scipy/optimize/zeros.py#L1220
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
â€¦ 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.
Indeed, in the last steps from:
https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms748_solve.hpp#L465,
â€¦ both the conditions are checked for, which is what I would expect
even in the intervening steps.
Now the lines seem to have originated in the very first commit
implementing this algorithm:
https://github.com/boostorg/math/commit/79a8199f9c26ba353fb52ec4543f75ffc2a8c95b
â€¦ but I do not see a way to contact the author jzmaddock other than
posting to this list, so I hope someone/they see here and reply.
Thanks!
 Shriramana Sharma à®¶à¯à®°à¯€à®°à®®à®£à®¶à®°à¯à®®à®¾ à¤¶à¥à¤°à¥€à¤°à¤®à¤£à¤¶à¤°à¥à¤®à¤¾ ð‘€°ð‘†ð‘€ð‘€»ð‘€ð‘€«ð‘€¡ð‘€°ð‘€ð‘†ð‘€«ð‘€¸
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