[R] analytic solution for equation

[Gabor Grothendieck]

Stephane Dray <dray <at> biomserv.univ-lyon1.fr> writes:
: 
: Hello,
: I have search on R website but do not find any solution.
: I would like to know if R has some functionalities to produce analytical 
results
: of equation. or more generally if it contains some functions to simplify 
equation.
: 
: For example:
: I would like to obtain x1 from:
: x1+x2=8  (x1=8-x2)
: 
: x1^2+x2=8 (x1=sqrt(8-x2))
: 
: Is is possible in R ? if not, do you know a (free) software that could do the 
job ?

I don't think R has this capability built in but you could try a computer
algebra system.  Yacas (http://yacas.sourceforge.net) as well as a number
of others are free.  Here is your calculation in yacas:

C:\yacas>yacas
True;
This is Yacas version '1.0.54'.
Yacas is Free Software--Free as in Freedom--so you can redistribute Yacas or
modify it under certain conditions. Yacas comes with ABSOLUTELY NO WARRANTY.
See the GNU General Public License (GPL) for the full conditions.
See http://yacas.sf.net for more information and documentation on Yacas.

Numeric mode: "Internal"
To exit Yacas, enter  Exit(); or quit or Ctrl-c. Type ?? for help.
Or type ?function for help on a function.
Type 'restart' to restart Yacas.
To see example commands, keep typing Example();
In> Solve(x1+x2==8,x1);
Out> 8-x2;
In> Solve(x1^2+x2==8,x1);
Out> (8-x2)^(1/2);