general inverse solver?
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 ---- Postscript "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." <http://mathsrv.ku-eichstaett.de/MGF/homes/grothmann/euler/>
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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