Apropos:
I don't have the problems, the OP had, but on my ubuntu
notebook, Ryacas does not return expressions (just the strings),
and hence
as.expression( <yacas-result> )
always gives NULL and e.g. the demo(Ryacas-Function)
also fails:
> yacas(expression(deriv(BurrCDF(x,c,k))))
k*c*x^(c-1)*(x^c+1)^(-(k+1));
> yy <- yacas(expression(deriv(BurrCDF(x,c,k))))
> yy
k*c*x^(c-1)*(x^c+1)^(-(k+1));
> str(yy)
List of 2
$ : NULL
$ YacasForm: chr "k*c*x^(c-1)*(x^c+1)^(-(k+1));"
- attr(*, "class")= chr "yacas"
>
I have
- yacas 1.2.2 (standard ubuntu package)
- re-installed Ryacas (manually from source, just now,
under R 2.15.0 patched)
> sessionInfo()
R version 2.15.0 Patched (2012-04-09 r58947)
Platform: x86_64-unknown-linux-gnu (64-bit)
locale:
[1] LC_CTYPE=de_CH.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8
[4] LC_COLLATE=de_CH.UTF-8 LC_MONETARY=en_US.UTF-8
LC_MESSAGES=de_CH.UTF-8
[7] LC_PAPER=C LC_NAME=C LC_ADDRESS=C
[10] LC_TELEPHONE=C LC_MEASUREMENT=de_CH.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] graphics grDevices datasets stats utils methods base
other attached packages:
[1] Ryacas_0.2-11 XML_3.9-4 fortunes_1.5-0 sfsmisc_1.0-20
loaded via a namespace (and not attached):
[1] compiler_2.15.0 tools_2.15.0
>
------------------------------------------------------------------
On our Fedora computers at work (with an *older* version of yacas,
installed manually from sources there),
things work fine :
> str(yacas(expression(Factor(x^2-1))))
List of 2
$ text : expression((x + 1) * (x - 1))
$ OMForm: chr [1:15] "<OMOBJ>" " <OMA>" " <OMS cd=\"arith1\"
name=\"times\"/>" " <OMA>" ...
- attr(*, "class")= chr "yacas"
> as.expression(yacas(expression(Factor(x^2-1))))
expression((x + 1) * (x - 1))
>
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
