[ADMB Users] Using asin with df1b2variables

Ben Stevenson bcs5 at st-andrews.ac.uk
Mon Oct 21 03:24:17 PDT 2013

Hi Dave,

Cool, thanks for the advice. I'll try and code up what you suggest.

I'd originally used atan instead of asin, but when I invoked the derivative
checker they were all wrong. I assume this is because of the instability
you mention. They were good with asin, though, which is why I changed.



On 20 October 2013 02:51, Ben Stevenson <bcs5 at st-andrews.ac.uk> wrote:

> Hi Dave,
> You're right, there is nothing wrong with asin(). It performs exactly as
> one would expect, I was not suggesting otherwise. The problem still remains
> of calculating a bearing in the range (0, 2*pi) between two locations that
> are defined by df1b2variables. The way I describe above appears to work but
> just seems really messy. Good point about an animal moving exactly north,
> though, I hadn't thought of that. Presumably so long as I keep the start
> values away from a north bearing I should be OK; I'd imagine it'd be very
> bad luck for a bearing to be allocated as exactly north during the
> optimisation.
> Cheers,
> Ben
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