Re: bad performance of Reduce (5.2)

*To*: mathgroup at smc.vnet.net*Subject*: [mg78089] Re: bad performance of Reduce (5.2)*From*: m.r at inbox.ru*Date*: Fri, 22 Jun 2007 06:50:06 -0400 (EDT)*References*: <200706160734.DAA26018@smc.vnet.net>

On Jun 17, 5:08 am, Andrzej Kozlowski <a... at mimuw.edu.pl> wrote: > > On second thoughts: there is probably not much point in testing the > condition that Reduce "assumed" numerically because I am sure Reduce > had already done so, and assumed tha tit holds precisely because it > passed all numerical tests at its disposal. Nevertheless, I still > think that the user should be able to access the full condition that > has been assumed, for reasons that seem to me to obvious to need > stating. > > AndrzejKozlowski It's often convenient to set $MessagePrePrint to InputForm (or unset it): In[1]:= Block[{$MessagePrePrint = InputForm}, Reduce[Sin[ArcTan[z] + ArcTan[2*z]] == 1/Sqrt[2] && z > 0, z, Reals]] During evaluation of In[1]:= Reduce::ztest: Unable to decide whether \ numeric quantities HoldForm[{(Pi - 4*ArcTan[(-3 + Sqrt[17])/4] - \ 4*ArcTan[(-3 + Sqrt[17])/2])/4, (3*Pi - 4*ArcTan[(3 + Sqrt[17])/4] - \ 4*ArcTan[(3 + Sqrt[17])/2])/4}] are equal to zero. Assuming they are. Out[1]= z == 1/4 (-3 + Sqrt[17]) || z == 1/4 (3 + Sqrt[17]) Maxim Rytin m.r at inbox.ru

**Follow-Ups**:**Re: Re: bad performance of Reduce (5.2)***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>

**References**:**bad performance of Reduce (5.2)***From:*dimitris <dimmechan@yahoo.com>