MaplePrimes - answers and comments on Question, ODE system

singularity

Joe Riel — Tue, 02 Mar 2010 05:17:51 Z

Maybe this will help:

plots[odeplot](sol1, [z, denom(rhs(eqn3))], 0 .. 1);

thanks rob, however this

bradders — Wed, 03 Mar 2010 19:43:28 Z

thanks rob,

however this doesnt solve the problem-singularity stil exists

mathematical singularity

bradders — Thu, 04 Mar 2010 02:10:01 Z

the singularity is only mathematical, it has no physical meaning it is however just a by product of the new way i have foremed this evolutionary situation. do you or anyone know of a way to keep maple plotting

cheers

chris

thanks, it seems to be when

bradders — Tue, 02 Mar 2010 16:54:50 Z

thanks,

it seems to be when thsi denominator goes to zero(obveriously! thanks lol) BUT i want maple to ignore this an just keep plottin out the other side of the singularity, can i gat it do do that??

cheers

Crossing a singularity

Robert Israel — Tue, 02 Mar 2010 21:23:09 Z

Leaving aside the question of what it means to "just keep plottin out the other side of the singularity", one way is to use a change of variables to get a system that won't have a singularity there. In your case, with the problem occurring when e(z) hits 0, you might try a new variable g(z) = 1/e(z) instead of e(z).

Singularity

Robert Israel — Thu, 04 Mar 2010 01:54:50 Z

Ahh.. the problem wasn't e(z) becoming 0, it was e(z)^2 - 0.27*(1+z)^3 becoming 0.

Unfortunately, it seems to me that f will become unbounded as this approaches 0. So I really doubt that the question of continuing beyond the singularity can have any meaningful answer.