[R] Query on finding root

[Ben Bolker]

(I mean pdavies)

On Mon, Aug 28, 2023, 7:52 AM Ben Bolker <bbolker using gmail.com> wrote:

> I would probably use the built in qdavies() function...
>
> On Mon, Aug 28, 2023, 7:48 AM Leonard Mada via R-help <
> r-help using r-project.org> wrote:
>
>> Dear R-Users,
>>
>> Just out of curiosity:
>> Which of the 2 methods is the better one?
>>
>> The results seem to differ slightly.
>>
>>
>> fun = function(u){((26104.50*u^0.03399381)/((1-u)^0.1074444)) - 28353.7}
>>
>> uniroot(fun, c(0,1))
>> # 0.6048184
>>
>> curve(fun(x), 0, 1)
>> abline(v=0.3952365, col="red")
>> abline(v=0.6048184, col="red")
>> abline(h=0, col="blue")
>>
>>
>>
>> fun = function(u){ (0.03399381*log(u) - 0.1074444*log(1-u)) -
>> log(28353.7/26104.50) }
>> fun = function(u){ (0.03399381*log(u) - 0.1074444*log1p(-u)) -
>> log(28353.7/26104.50) }
>>
>> uniroot(fun, c(0,1))
>> # 0.6047968
>>
>> curve(fun(x), 0, 1)
>> abline(v=0.3952365, col="red")
>> abline(v=0.6047968, col="red")
>> abline(h=0, col="blue")
>>
>> Sincerely,
>>
>> Leonard
>>
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>>
>

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