Yes thank you, I realised this last night also :) It's pretty much exactly what I was looking for, so thanks!
On Saturday, 29 June 2013 07:36:46 UTC+10, Aaron Meurer wrote: > > You could solve for just two of the variables, like sym.solve((eq1, > eq2, eq3), (z, x)). > > Aaron Meurer > > On Fri, Jun 28, 2013 at 3:56 PM, Ondřej Čertík > <ondrej...@gmail.com<javascript:>> > wrote: > > Hi Thomas, > > > > On Thu, Jun 27, 2013 at 8:32 PM, Thomas Moore > > <tomm...@live.com.au<javascript:>> > wrote: > >> I'm contemplating using sympy in a program which will need to > symbolically > >> solve a set of simultaneous and possibly non-linear equations. However, > it's > >> obviously not possible to find symbolic solutions in many cases, but if > >> sym.solve can't find an explicit solution what I'd really like is for > some > >> way of delivering a simplified set of simultaneous equations. > >> > >> Let me give an example which gives me some hope: > >> > >> eq1 = x + y - sym.log(x) - 3 > >> eq2 = x**2 + z**2 - 4 > >> eq3 = x + y - 15*z - 100 > >> > >> sym.solve((eq1, eq2, eq3), (x,y,z)) > >> > >> Obviously this is going to be tough to solve completely, and Sympy does > >> fail, but the error I recieve is: > >> > >> NotImplementedError: could not solve 15*z - log(sqrt((-z + 2)*(z + > 2))) > >> + 97 > >> > >> And it looks like, under the hood, Sympy has in fact almost completely > >> simplified the equations. We have an equation in terms of z alone, and > >> (hopefully) we could have a second equation in terms of x and z and > then a > >> third equation in terms of all three variables. > >> > >> I'm just wondering if there is some function within sympy to simplify > sets > >> of simultaneous equations by eliminating variables. > > > > I don't know how to do that, apart from manually substituting one > > equation into the other. > > Do you know the structure of your equations? > > > > How do you generate them, where do they come from? Maybe it is > > possible to design an algorithm that can do what you want. > > > > Ondrej > > > > -- > > You received this message because you are subscribed to the Google > Groups "sympy" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to sympy+un...@googlegroups.com <javascript:>. > > To post to this group, send email to sy...@googlegroups.com<javascript:>. > > > Visit this group at http://groups.google.com/group/sympy. > > For more options, visit https://groups.google.com/groups/opt_out. > > > > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
