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Author rhettinger
Recipients davin, mark.dickinson, rhettinger, serhiy.storchaka, tim.peters
Date 2017-10-01.17:53:44
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Message-id <1506880424.68.0.213398074469.issue31630@psf.upfronthosting.co.za>
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Content 
I would have thought this would be a straight pass-through to the underlying hardware FPU tan() instruction so that it would give the same answer for the same hardware regardless of O/S.

Perhaps we're seeing a software-only implementation (using CORDIC or somesuch).  If so, inputs close to a singularity are the place where the implementation is likely to fall apart (the relative error in this example is 1.000004001955473).

* https://www.gnu.org/software/libc/manual/html_node/Errors-in-Math-Functions.html
* https://stackoverflow.com/questions/16880376/sin-cos-tan-not-accurate
* http://code.activestate.com/recipes/576792-polar-to-rectangular-conversions-using-cordic/
History
Date User Action Args
2017-10-01 17:53:44rhettingersetrecipients: + rhettinger, tim.peters, mark.dickinson, serhiy.storchaka, davin
2017-10-01 17:53:44rhettingersetmessageid: <1506880424.68.0.213398074469.issue31630@psf.upfronthosting.co.za>
2017-10-01 17:53:44rhettingerlinkissue31630 messages
2017-10-01 17:53:44rhettingercreate