Re: NDSolve is using Solve?
- To: mathgroup at smc.vnet.net
- Subject: [mg117074] Re: NDSolve is using Solve?
- From: "J.Frazer" <j.frazer at sussex.ac.uk>
- Date: Wed, 9 Mar 2011 06:58:34 -0500 (EST)
- References: <0CF1B1A9-BEEE-40E2-A1E1-8370648FD55D@sussex.ac.uk>
Ok so I have one idea. I read that restricting the function definition to be something like f[x_?NumericQ,y_?NumericQ] can enable you to avoid symbolic evaluation, speeding up the calculation by a factor of 10000 or so! My issue now is that I have functions that are defined in terms of derivatives of other previously defined functions, so I won't be able to blindly go through changing the function definitions. I suppose this means I will have to rewrite everything which will probably take me a couple of days. Given that I'm not even sure if this will work, any suggestions at this point would be very much welcome. Cheers, Jonny On 8 Mar 2011, at 12:17, J.Frazer wrote: > Hello everyone, > > This is my first time posting so my apologies if I'm going about this the wrong way. I'm having the following problem: > > I'm using NDSolve but its not managing to get to the solution even if I leave it running over the weekend. If I greatly simplify one of the equations I can get a result but in either case I get the error messages > > Solve:: incnst > Solve:: ifun > > This worries me as if its trying to simplify analytically, presumably as the equations becomes more complicated this will become incredibly time consuming. > > Do people agree this may be the cause of the long running time? If so, is there a way of stopping NDSolve from using Solve? > > Cheers, > > Jonny