[R] Solving equation

[Berend Hasselman]

David Winsemius wrote:
> 
> 
> 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.
> ...
> 

You could also try package nleqslv (intended for solving equations).
But also try f(0)

Berend
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