R help - Jun 2009 - Problem : solving a equation with R , fail with uniroot function

Hi ,
I would like to know if a R function have the same behaviour than the matlab
solve function.
I tried something with uniroot but I have some problems:
The equation I need to solve is :
exp(c0-r0)*(bb0+x)*(bb1-x)=(bb0+x+1)(bb1-x-1)

So I tried this:

STEP 1: my function test
 test <- function(x,bb0=-3,bb1=5,c0=2,r0=0) {
+ ((exp(c0-r0)*(bb0+x)*(bb1-x))/((bb0+x+1)(bb1-x-1))-1)}

STEP 2:
> uniroot(test,c(-100,100))$root*
Erreur dans f(lower, ...) :
  tentative d'appliquer un objet qui n'est pas une fonction*

R tells me that test is not a function ...

STEP 3:
> is.function(test)
[1] TRUE


Thanks,
Yann

	[[alternative HTML version deleted]]

Tena koe Yann

It may not be the only problem, but you are missing an operator between
(bb0+x+1) and (bb1-x-1).

HTH ....

Peter Alspach
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of yann lancien
> Sent: Wednesday, 10 June 2009 9:31 a.m.
> To: r-help at r-project.org
> Subject: [R] Problem : solving a equation with R , fail with 
> uniroot function
> 
> Hi ,
> I would like to know if a R function have the same behaviour 
> than the matlab solve function.
> I tried something with uniroot but I have some problems:
> The equation I need to solve is :
> exp(c0-r0)*(bb0+x)*(bb1-x)=(bb0+x+1)(bb1-x-1)
> 
> So I tried this:
> 
> STEP 1: my function test
>  test <- function(x,bb0=-3,bb1=5,c0=2,r0=0) {
> + ((exp(c0-r0)*(bb0+x)*(bb1-x))/((bb0+x+1)(bb1-x-1))-1)}
> 
> STEP 2:
> > uniroot(test,c(-100,100))$root*
> Erreur dans f(lower, ...) :
>   tentative d'appliquer un objet qui n'est pas une fonction*
> 
> R tells me that test is not a function ...
> 
> STEP 3:
> > is.function(test)
> [1] TRUE
> 
> 
> Thanks,
> Yann
> 
> 	[[alternative HTML version deleted]]
> 
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