[R] evaluation of equations from Ryacas

[Søren Højsgaard]

Dear Erin,

Not exactly elegant, but

> e<-expression(list(R == 100 * (1 - 2 * y/10000)))
> ee <- e[[1]][2]
> ee
(R == 100 * (1 - 2 * y/10000))()
> eval(parse(text=(substring(paste(ee), 5))), list(y=5))
[1] 99.9

Regards
Søren


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Erin Hodgess
Sent: 19. juni 2013 07:03
To: R help
Subject: [R] evaluation of equations from Ryacas

Hello again.

Now I have the following:
> xx
[1] "Solve(1 - R/100==(2*y)/10000,R)"
> yacas(xx)
expression(list(R == 100 * (1 - 2 * y/10000)))
>

I would like to put in a value for y and obtain R.
I've tried more stuff with eval and Eval, but no luck yet.

Any suggestions would be much appreciated.

Thanks,
Erin


--
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences University of Houston - Downtown
mailto: erinm.hodgess at gmail.com

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