According to checkodesol(paraChute, solution), the solution is correct. Aaron Meurer
On Tue, Jun 28, 2016 at 2:13 AM, Dan Lewis <[email protected]> wrote: > Hi folks, > > Looks like sympy/dsolve produces an incorrect solution to an ODE: > > from sympy import * > > mass, g, b, t = symbols('mass g b t') > > v, x = symbols('v x', cls=Function) > > paraChute = mass*v(t).diff(t)-mass*g+b*(v(t))**2 > > solution = dsolve(paraChute,v(t),hint='lie_group') > > solution > > Out[1]: > > Eq(v(t), sqrt(g)*sqrt(mass)/(sqrt(b)*tanh(sqrt(b)*sqrt(g)*(C1*mass + > t)/sqrt(mass)))) > > > Sorry in advance if I'm doing something silly - the solution shouldn't be > 1/tanh. Should be tanh. > > -- > 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 [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/92f8fe37-45df-4cc0-9ebc-7330f0bb20d9%40googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6%2BN5YNPe7FY_xCuVHYjSoXvU01vk%3DnwY37DfMNyjOo1LQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
