Message-ID: <16091bc726bb18999a039e4b48236a49@soc.soton.ac.uk>
Date: 2005-03-16T09:04:41Z
From: robin hankin
Subject: Trigonometric functions (PR#7728)
In-Reply-To: <Pine.A41.4.61b.0503151524570.383546@homer03.u.washington.edu>
On Mar 15, 2005, at 11:26 pm, Thomas Lumley wrote:
> On Wed, 16 Mar 2005, Peter Kleiweg wrote:
>
>> Thomas Lumley schreef op de 15e dag van de lentemaand van het jaar
>> 2005:
>>
>>
>>>> x<-sqrt(2)
>>>> asin(x^2-1)
>>>> result in:
>>>> NaN
>>>
>
The way I would deal with this would be to force asin() to work in
complex mode:
> x <- sqrt(2)
> asin(x^2-1+0i)
[1] 1.570796+2.980232e-08i
>
(the error is large because the derivative of arcsin is infinite at
x=1).
--
Robin Hankin
Uncertainty Analyst
Southampton Oceanography Centre
European Way, Southampton SO14 3ZH, UK
tel 023-8059-7743