R SIG Debian - Oct 2006 - New package Ryacas

Ryacas is an R interface to the free yacas computer algebra
system.  Ryacas allows one to send R expressions,
unprocessed yacas strings and certain other R objects to a
separate yacas process from R and get back the result.  It
also has facilities for manipulating yacas strings and R
expressions destined for yacas processing.

It can be used for exact arithmetic, symbolic math, ASCII
pretty printing and translating R to TeX.


Online info.  For overview, pointers to additional
information, installation instructions and a sample session
see:

    http://code.google.com/p/ryacas/

The vignettes can be viewed online here:

    http://ryacas.googlecode.com/svn/trunk/inst/doc/Ryacas.pdf
    http://ryacas.googlecode.com/svn/trunk/inst/doc/Ryacas-Sym.pdf


More. Once Ryacas is installed, pointers to additional
information can be found with these R commands:

    library(Ryacas)
    package?Ryacas


---

Rob Goedman, goedman at mac dot com
Gabor Grothendieck, ggrothendieck at gmail dot com
S?ren H?jsgaard, Soren.Hojsgaard at agrsci dot dk
Ayal Pinkus, apinkus at xs4all dot nl

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Hello,

First,
I would like to congratulations for very cool package! It's very 
nice
idea!...
Secondly,
Is there a way to send R'objects (variables) to yacas and make 
symbolic
operations??
for example:

d <- diag(3)
a <- "A"

yacas(   d * a )

Thanks,
Cleber Borges


Gabor Grothendieck wrote:
>Ryacas is an R interface to the free yacas computer algebra
>system.  Ryacas allows one to send R expressions,
>unprocessed yacas strings and certain other R objects to a
>separate yacas process from R and get back the result.  It
>also has facilities for manipulating yacas strings and R
>expressions destined for yacas processing.
>
>It can be used for exact arithmetic, symbolic math, ASCII
>pretty printing and translating R to TeX.
>
>
>Online info.  For overview, pointers to additional
>information, installation instructions and a sample session
>see:
>
>    http://code.google.com/p/ryacas/
>
>The vignettes can be viewed online here:
>
>    http://ryacas.googlecode.com/svn/trunk/inst/doc/Ryacas.pdf
>    http://ryacas.googlecode.com/svn/trunk/inst/doc/Ryacas-Sym.pdf
>
>
>More. Once Ryacas is installed, pointers to additional
>information can be found with these R commands:
>
>    library(Ryacas)
>    package?Ryacas
>
>
>---
>  
>

Hello Gabor

I try these example, but I obtain some errors.


*First example*
> yacas("a * Identity(3)")
expression(list(list(a, 0, 0), list(0, a, 0), list(0,
0, a)))

 it's ok , but the next command:
> PrettyForm("%")
Error in PrettyForm("%") : no applicable method for
"PrettyForm"
>
If I make a little modification ( set a variable in
YACAS), I obtain right behavior.
> yacas("TEST := a * Identity(3)")
expression(list(list(a, 0, 0), list(0, a, 0), list(0,
0, a)))
>
> yacas("PrettyForm(TEST)")
/                    \
| ( a ) ( 0 ) ( 0 )  |
|                    |
| ( 0 ) ( a ) ( 0 )  |
|                    |
| ( 0 ) ( 0 ) ( a )  |
\                    /
>
I make a test for all example in "Ryacas.pdf" and all
works for me! :-)


*Second example*
> d <- List(List(1, 0, 0), List(0, 1, 0), List(0, 0,
1))
Error in List(1, 0, 0) : no applicable method for
"List"
>
> d <- yacas( "List(List(1, 0, 0), List(0, 1, 0),
List(0, 0, 1))" )
> d
expression(list(list(1, 0, 0), list(0, 1, 0), list(0,
0, 1)))
>
GUESS:
When I use the commands whitout yackas() statement,
the error raise up.
> a <- Sym("a")
> a * d
a * list( list( 1 , 0 , 0 ) , list( 0 , 1 , 0 ) ,
list( 0 ,
0 , 1 ) )
> PrettyForm("%")
Error in PrettyForm("%") : no applicable method for
"PrettyForm"
>
> yacas("PrettyForm(%)")
a * list( list( 1 , 0 , 0 ) , list( 0 , 1 , 0 ) ,
list( 0 ,
0 , 1 ) )



Thanks for your attention!


Cleber Borges



>Here is a slightly shorter way to do it although it
involves passing
>a yacas string directly:
>
>>yacas("a * Identity(3)")
>
>expression(list(list(a, 0, 0), list(0, a, 0), list(0,
0, a)))
>
>>PrettyForm("%")
>
>/                    \
>| ( a ) ( 0 ) ( 0 )  |
>|                    |
>| ( 0 ) ( a ) ( 0 )  |
>|                    |
>| ( 0 ) ( 0 ) ( a )  |
>\                    /
>
>
>On 10/16/06, Gabor Grothendieck
<ggrothendieck em gmail.com> wrote:
>
>>Its pretty limited right now but you can do this:
>>
>>>library(Ryacas)
>>>d <- List(List(1, 0, 0), List(0, 1, 0), List(0, 0,
1))
>>>a <- Sym("a")
>>>a * d
>>
>>expression(list(list(a, 0, 0), list(0, a, 0),
list(0, 0, a)))
>>
>>>PrettyForm("%")
>>
>>/                    \
>>| ( a ) ( 0 ) ( 0 )  |
>>|                    |
>>| ( 0 ) ( a ) ( 0 )  |
>>|                    |
>>| ( 0 ) ( 0 ) ( a )  |
>>\                    /
>>
>>The ASCII representation of the matrix will look
correct in R although its
>>possible that the email process munges it up so it
may not look right
>>when you receive this.
>>
>>Also there are also matrix examples on the home
page, in the Ryacas vignette
>>and in the Ryacas-Sym vignette.
>>
>>Note that by mistake the vignette labelled
Ryacas-Sym in the package
>>itself is actually a copy of the Ryacas vignette so
to see the actual
>>Ryacas-Sym vignette currently one must look at the
one in the source repository:
>>http://ryacas.googlecode.com/svn/trunk/inst/doc/Ryacas-Sym.pdf
>>
>>
>>
>>On 10/16/06, Cleber N. Borges
<cborges em iqm.unicamp.br> wrote:
>>
>>>Hello,
>>>
>>>First,
>>>I would like to congratulations for very cool
package! It's very
>>>nice
>>>idea!...
>>>Secondly,
>>>Is there a way to send R'objects (variables) to
yacas and make
>>>symbolic
>>>operations??
>>>for example:
>>>
>>>d <- diag(3)
>>>a <- "A"
>>>
>>>yacas(   d * a )
>>>
>>>Thanks,
>>>Cleber Borges
>>>
>>>