Re: A strange bug in Solve

*To*: mathgroup at smc.vnet.net*Subject*: [mg24482] Re: A strange bug in Solve*From*: Warren Wolfe <"75127,1531"@compuserve.com>*Date*: Wed, 19 Jul 2000 01:21:55 -0400 (EDT)*References*: <8k9iar$fpo@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Andrzej Kozlowski wrote: > I have long ago learned to be careful when making claims about kernel bugs > in Mathematica, but this time I am pretty sure I have found a fairly serious > one, even though it looks rather strange. > > I asked Mathematica to solve a system of two trigonometric equations: > > In[1]:= > eqns = {2*Cos[2*t]*Cos[u/2] + Cos[t]*Sin[u/2] == 0, > (Cos[u/2]*Sin[t])/2 - (Sin[2*t]*Sin[u/2])/2 == 0}; > > To my surprise Solve returned the empty list (I knew these equations do have > solutions for geometric reasons): > > In[2]:= > Solve[eqns, {u, t}] > Out[2]= > {} > When I tried this problem using Mathematica 3.0 for Windows it found 8 solutions and also gave the Solve::ifun message. There was no need for Simplify.