R help - Jun 2010 - code for power and suffix for x,y labels in plot( ).

Hi 

I was trying to have a graph whose axes are X axis: m, Y axis: var[X ((a,b) in
suffix, and (n,d) in the power)].

X ((a,b) in suffix, and (n,d) in the power)-        X^(n,d) _ (a,b).

Actually I require many plots involving different values of a,b,n,d, so need to
keep this complicated notation.
The expression() didn't work out for this case. Can anyone help me out. 
Thanks, in advance.
Shant






uniroot(function(x) x*(3^x)*log(4)-x*log(4/3)-(3^x)+1, lower = -2, upper = 2,
tol = 0.001 )

While using this I am getting the following error. Can anyone please help me
out.
Error in uniroot(function(x) x * (3^x) * log(4) - x * log(4/3) - (3^x) +  :  
f() values at end points not of opposite sign.

Thanks in advance.

Shant


      
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On Tue, Jun 1, 2010 at 9:59 PM, Shant Ch <sha1one at yahoo.com>
wrote:
> Hi
>
> I was trying to have a graph whose axes are X axis: m, Y axis: var[X ((a,b)
in suffix, and (n,d) in the power)].
>
> X ((a,b) in suffix, and (n,d) in the power)- ? ? ? ?X^(n,d) _ (a,b).
>
> Actually I require many plots involving different values of a,b,n,d, so
need to keep this complicated notation.
> The expression() didn't work out for this case. Can anyone help me out.
> Thanks, in advance.
> Shant
>
>
>
>
>
>
> uniroot(function(x) x*(3^x)*log(4)-x*log(4/3)-(3^x)+1, lower = -2, upper =
2, tol = 0.001 )
>
> While using this I am getting the following error. Can anyone please help
me out.
> Error in uniroot(function(x) x * (3^x) * log(4) - x * log(4/3) - (3^x) + ?:
? f() values at end points not of opposite sign.
Here is your function:

temp.fun <- function(x) {
  value <- x*(3^x)*log(4)-x*log(4/3)-(3^x)+1
  return(value)
}

look what happens when you do:

temp.fun(-2)
temp.fun(2)

in both cases, it returns a positive value.  uniroot() requires "The
function values at the endpoints must be of opposite signs (or zero)",
hence the error.  I believe your function has a lower bound of 0,
which is obtained when the input is 0.  So one option would be to
change your argument to uniroot() so that lower=0.  Although the
results are not particularly interesting in this case.

uniroot(function(x) x*(3^x)*log(4)-x*log(4/3)-(3^x)+1, lower = 0,
upper = 2, tol = 0.001 )

HTH,

Josh
>
> Thanks in advance.
>
> Shant
>
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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-- 
Joshua Wiley
Senior in Psychology
University of California, Riverside
http://www.joshuawiley.com/