[ADMB Users] eigenvectors of the Hessian and parameter errors

[David Holmgren]

Hi - Sorry for the late reply.  I've got another model formulation which I think will help.  Thanks for the advice!

Dave H.

On 2011-10-07, at 12:59 PM, dave fournier wrote:

> On 11-10-07 11:42 AM, David Holmgren wrote:
> 
> 
> Well if you want to send me what I need to run the model, I'll take a quick look at it.
> 
> 
>> Thanks.  The model formulation could indeed be the problem.  I should also say that the four negative eigenvalues are all small, i.e., on the order of -1e-08 or less.
>> 
>> Dave H.
>> 
>> On 2011-10-07, at 12:20 AM, dave fournier wrote:
>> 
>>> On 11-10-06 09:01 PM, David Holmgren wrote:
>>> 
>>> OK,
>>> 
>>> In that case you have a problem. So either you are not at a minimum or the way
>>> the model is formulated it can not get quite close enough to make the Hessian positive definite.
>>> 
>>>          Dave
>>> 
>>>> Many thanks!  It is usually the case that four of 24 eigenvalues are negative.  I'm not fixing any parameters, or doing the minimization in phases.
>>>> 
>>>> Dave H.
>>>> 
>>>> On 2011-10-06, at 8:27 AM, dave fournier wrote:
>>>> 
>>>>> I sent this once but it seems to have disappeared .. so again
>>>>> 
>>>>> The error gets printed out in two cases I think.  1.) if the eigenvalues of the Hessian are not positive.
>>>>> 2) If the  std dev of a dependent variables computed by the delta method is not positive. However
>>>>> if that parameter is not active then the message will get produced since its gradient is 0.
>>>>> There was some attempt to make this a bit less confusing at some time, but maybe it died somewhere.
>>>>> _______________________________________________
>>>>> Users mailing list
>>>>> Users at admb-project.org
>>>>> http://lists.admb-project.org/mailman/listinfo/users
>>>> David Holmgren
>>>> holmgren at telus.net
>>>> 
>>>> 
>>>> 
>>>> 
>> David Holmgren
>> holmgren at telus.net
>> 
>> 
>> 
>> 
> 

David Holmgren
holmgren at telus.net