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Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!petrus!bellcore!decvax!tektronix!hplabs!sdcrdcf!randvax!George J. Carrette <GJC@MIT-MC.ARPA>
From: George J. Carrette <GJC@MIT-MC.ARPA>
Newsgroups: net.math.symbolic
Subject: Re: Speeding up Macsyma
Message-ID: <2667@randvax.UUCP>
Date: Mon, 26-Aug-85 13:21:40 EDT
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Posted: Mon Aug 26 13:21:40 1985
Date-Received: Sun, 1-Sep-85 12:53:57 EDT
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The Macsyma command FORTRAN can indeed create fortran code
fragments from symbolic expressions in macsyma. These can
be edited into a fortran function or main program. The FORT
command in MAX$DISK:[LPH]FORT.MC (in the DOE-MACSYMA release)
gets rid of the editing step in many cases by generating the
FUNCTION, RETURN, and END statements for you. However, even
that may not be worth the bother if you only want reasonable
efficiency in numerical code for calling the 3-D plot command
or contourplot or the ROMBERG numerical integrator, all of which
may evaluate a given expression many many times. The use of
the Macsyma->Lisp translator and Lisp->Machine-code compiler may
be all that is required. Here is an example from the PLOT DEMO:

(X^3+Y^4-0.2*X)*EXP(-X^2-Y^2)+0.3*EXP(-(X-1.225)^2-Y^2);
PLOT3D(%,X,-3,3,Y,-3,3)$

If instead we define a function:
F(X,Y):=(MODE_DECLARE([X,Y],FLOAT),
         (X^3+Y^4-0.2*X)*EXP(-X^2-Y^2)+0.3*EXP(-(X-1.225)^2-Y^2));

And:
TRANSLATE(F); COMPILE(F);

Then the PLOT3D will go noticably faster as
PLOT3D(F(X,Y),X,-3,3,Y,-3,3);

Files of Macsyma source code are translated and compiled with the
TRANSLATE_FILE and COMPILE_LISP_FILE commands.

-gjc