[R] general inverse solver?

Hans W. Borchers hwborchers at googlemail.com
Tue Feb 10 08:33:00 CET 2009

I know that Ryacas is promoted here whenever requests about symbolic algebra
or calculus appear on the R-help list. But to say the truth, Yacas itself is
a very very limited Computer Algebra System and looking onto its home page
it appears the development will stop or has stopped anyway.

It would be fair to clearly state that there is no R package to solve
somewhat more involved symbolic mathematical problems. One could then point
the requestor to one of the open source Computer Algebra Systems  (CAS) such
as Maxima or Axiom.

Interestingly, the free Math Toolbox Euler by Grossmann has integrated
Maxima into its numerical environment in a way that is really useful for
numerical and symbolic computations. I could imagine that in a similar way
Maxima can be integrated into R bringing the full power of computer algebra
to the R community.

Hans W. Borchers
ABB Corporate Research


"The Euler Mathematical Toolbox is a powerful, versatile, and open source
software for numerical and symbolic computations ... Euler supports symbolic
mathematics using the open algebra system Maxima."


Gabor Grothendieck wrote:
> The forms of equations are limited but its not limited to just one:
>> library(Ryacas)
> Loading required package: XML
>> x <- Sym("x")
>> y <- Sym("y")
>> Solve(List(x+y == 2, x-y == 0), List(x, y))
> [1] "Starting Yacas!"
> expression(list(list(x == 2 - y, y == 1)))
> On Mon, Feb 9, 2009 at 7:45 PM, Carl Witthoft <carl at witthoft.com> wrote:
>> Gabor G a ecrit:
>> Check out the Ryacas package.   There is a vignette with some
>> examples.
>> ----
>> Which led me to the manuals for yacas itself.  I'm guessing there may be
>> a
>> way to use yacas'  "AND" construct to combine a few equations and then
>> hope
>> the Newton Solver can work with that, but it's not clear that will work.
>> TK!Solver is nice because you aren't limited to linear equations, nor to
>> equations which "fit" into a matrix structure, and because it's legal to
>> have more than one unknown to be back-solved (assuming the problem is not
>> under- or over-defined, of course).
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