[R] Solving equation

[David Winsemius]

On May 1, 2010, at 3:28 AM, Berend Hasselman wrote:

>
>
> Shant Ch wrote:
>>
>> I want to solve: x*(3^x)*log(4)-x*log(4/3)-(3^x)+1=0 for x. I used  
>> the
>> following code,
>>
>> 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.
>>

> Try f(-2) and f(2) and you'll see the cause of the error message.
> Define your equation as a function
>
> f <- function(x) return(x*(3^x)*log(4)-x*log(4/3)-(3^x)+1)
>
> and do
>
> curve(f,from=-2,to=2)
>
> curve(f,from=-.1,to=.1)
>
> and draw your conclusions.


Try optimize instead.

-- 
David.


>
> Berend
> -- 
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>
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David Winsemius, MD
West Hartford, CT