From: Stavros Macrakis <macrakis@al...>  20140331 13:50:22

Can you assume that Vmax>0? If so, ratsimp(imagpart(erg[1])) simplifies to 0. On Sat, Mar 29, 2014 at 10:54 AM, velten <kai.velten@...> wrote: > Thanks, I'll try that. You are probably right that real_p(e) won't work > on complex expressions, and I will probably have to keep my current > workaround for complex expression, which is plotting imagpart e.g. using > plot3d over the subset of the parameter space where I expect imagpart=0. > > Kai > > > > > > > Original Message > From: Barton Willis <willisb@...> > To: velten <kai.velten@...>, andre maute <andre.maute@...> > Subject: RE: [Maximadiscuss] Can Maxima prove Im(x)=0? > Date: Sat, 29 Mar 2014 12:04:59 +0000 > > > 1. Can I somehow solve equations with assumptions similar to: > > assume(12*Vmax%pi*Lv^3<0); > > erg:solve((Lvbv)*%pi/4*bv^2+%pi/12*bv^3=Vmax,bv); > > Solve does not exclude solutions that do not satisfy the assumptions in > the fact database. > You could try using sublist on the solutions to find the solution that > satisfies certain inequalities. > > >2. Can Maxima prove imagpart(x)=0, if x is complex, depends on > >parameters a,b,c..., and the parameter space is restricted similar to > >the cubic example below. > > I'd say Maxima isn't capable of proving anything. You can certainly define > predicates such as > > real_p(e) := is(equal(imagpart(e),0)) > > For simple expressions, this function might work, but in general, I'd > guess that real_p will not > work as well as you would like it to work. > > > > Barton > > > >  > _______________________________________________ > Maximadiscuss mailing list > Maximadiscuss@... > https://lists.sourceforge.net/lists/listinfo/maximadiscuss > 