Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!scubed!s3dawn!esalbert
From: esalbert@s3dawn.ARPA (Eric Salberta)
Newsgroups: comp.lang.fortran
Subject: Re: Responses to M. Shapiro & K. Bierma
Message-ID: <1729@scubed.UUCP>
Date: 4 May 89 08:53:03 GMT
References: <24091@beta.lanl.gov> <50500126@uxe.cso.uiuc.edu>
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Reply-To: esalbert@s3dawn.UUCP (Eric Salberta)
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In article <50500126@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes:
>One cannot quibble with "Those folks really, really benefit from 
>good libraries." Pray tell me, where can I find some of these? 
>The only commercial or common public domain library routines I have
>found optimal for my use are the routines "tred2" and "tql2" from the
>EISPAC library. Can anyone recommend a library routine for integrating
>differential equations of the sort I use that is better than the 
>sixth order hybrid Gear fixed step size integrator I now use?
>I haven't found one to date. (A typical use would be 24 coupled equations
>with the subroutine evaluating the derivatives filling 300 lines
>with exp's, sqrt's, and tanh's. The solutions are quasi-periodic.)
>
>Doug McDonald

	One place that you might look is the book "Numerical Recipes: The Art
of Scientific Computing" by W. H. Press, B. P. Flannery, S. A. Teukolsky, and
W. T. Vetterling.  This book has several coupled differential equation
solvers, and while Gear is not one of them, they are (in general) not
limited to fixed step sizes.  I don't know if they would be better than Gear
for your application, but it couldn't hurt to look.  This book is very
good at explaining the traps and pitfalls of different methods, and has
become the first place that I look for many problems of this type.

Hope this helps.

						   Eric R. Salberta
						(esalbert@scubed.com)