Re: [boost] wrong result in complex pow

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 noticed that my simple patch with base=0>> doesn't work. Thanks Gero. Yes. I am trying a patch that handles zero explicitly.> I'm not quite sure if all zeros, NaNs and Infinities> are correct yet, Gero, I patched this about as far as I'd like to go for this particular issue, added relevanttests. Underway, I did find that morepossible work with zero, inf, NaN parametersthat *could* be done in that particular header,but I will not modify these at the moment.This is because there are not a lot of requestsfor changes. I'd probably end up breakingexisting code if I tried to clean up allkinds of edge cases that my eyes happenedacross. That being said, the exact issue that youhave pointed out and addressed in thisthread on the board is being handledin the PR here: https://github.com/boostorg/math/pull/507 ... with fixed code here:https://github.com/boostorg/math/blob/e3cc94a580f3d1282578b0c31f985a392c866f... Gero, if you get a chance, could yougive the patch a try? It will expectedly bemerged in and available in the next release. Kind regards, Chris On Sunday, January 31, 2021, 3:22:53 PM GMT+1, Christopher Kormanyos wrote:

noticed that my simple patch with base=0> doesn't work. Thanks Gero.

Yes. I am trying a patch that handles zero explicitly.I'm not quite sure if all zeros, NaNs and Infinitiesare correct yet,... But the patch is generallymoving toward the fix shown in the link below... If you get a chance, could you try that patchfrom the branch linked below? https://github.com/boostorg/math/blob/2eac693e12547c1ca26800c2403e4e50f62d29... Kind regards, Chris On Sunday, January 31, 2021, 2:17:32 PM GMT+1, Gero Peterhoff wrote: Hello Christopher, I just noticed that my simple patch with base=0 doesn't work. It is probably not that simple. https://godbolt.org/z/8Me15Y regards Gero Am 30.01.21 um 16:22 schrieb Christopher Kormanyos:

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 the pow-function pow(scalar, complex) in boost/math/cstdfloat/cstdfloat_complex_std.hpp get wrong result.

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Thanks Gero, I am on the go, but later today, I'll add this as an issue in Git and kick off the discussion for the fix with the colleagues.

A new issue can be found here, but it is not clear which code example elicits the unexpected behavior.

https://github.com/boostorg/math/issues/506 https://github.com/boostorg/math/issues/506

On Thursday, January 28, 2021, 12:55:59 PM GMT+1, Gero Peterhoff via Boost wrote:

Hello, the pow-function pow(scalar, complex) in boost/math/cstdfloat/cstdfloat_complex_std.hpp get wrong result.

Current implementation: inline complex pow(const BOOST_CSTDFLOAT_EXTENDED_COMPLEX_FLOAT_TYPE& x,                                                                 const complex& a) {   return std::exp(a * std::log(x)); }

I think that's correct: inline complex pow(const BOOST_CSTDFLOAT_EXTENDED_COMPLEX_FLOAT_TYPE& x,                                                                 const complex& a) {   return std::exp(a * std::log(complex(x))); }

regards Gero

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