R help - Mar 2013 - Error with grad() for numerical differential of a function

Hello everyone,

I have programmed a function and, among other things, it has to compute the
differential of a function. I have been using the function grad() and I have
programmed some simulated studies. I have testes with 72,576 different
combinations of the initial values and now I got an error in only 4 situations.

The error comes from the function grad() and I don't understand why. This is
the output:
Error in grad.default(Sstar, x = t, dist1 = T1pdist, dist2 = T2pdist,  : 
  function returns NA at
3.90625e-071.01927622979798e-087.7105723770202e-075.27096223871154e-087.28540377612885e-071.25230637383194e-076.56019362616806e-072.21329924168263e-075.59920075831737e-073.324709613353e-074.487790386647e-070.0001000016964206937.79553579306956e-072.72822299391765e-087.53967770060824e-078.56180755521809e-086.95631924447819e-071.70797994270076e-076.10452005729924e-072.75627788007242e-075.05622211992758e-07
distance from x.

Anyone knows when returns a NA this function? Anyone knows other function to
make numerical approximations of the differential?

Thank you for your help,
Oleguer
	[[alternative HTML version deleted]]

On 10-03-2013, at 16:43, Oleguer Plana Ripoll <oleguerplana at gmail.com>
wrote:
> Hello everyone,
> 
> I have programmed a function and, among other things, it has to compute the
differential of a function. I have been using the function grad() and I have
programmed some simulated studies. I have testes with 72,576 different
combinations of the initial values and now I got an error in only 4 situations.
> 
> The error comes from the function grad() and I don't understand why.
This is the output:
> Error in grad.default(Sstar, x = t, dist1 = T1pdist, dist2 = T2pdist,  : 
>  function returns NA at
3.90625e-071.01927622979798e-087.7105723770202e-075.27096223871154e-087.28540377612885e-071.25230637383194e-076.56019362616806e-072.21329924168263e-075.59920075831737e-073.324709613353e-074.487790386647e-070.0001000016964206937.79553579306956e-072.72822299391765e-087.53967770060824e-078.56180755521809e-086.95631924447819e-071.70797994270076e-076.10452005729924e-072.75627788007242e-075.05622211992758e-07
distance from x.
> 
> Anyone knows when returns a NA this function? Anyone knows other function
to make numerical approximations of the differential?
> 
> Thank you for your help,
> Oleguer
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
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Not enough information to give a non flippant reply.
Which package(s) are you using?
What is your function?
Provide a small reproducible example.

Please read the posting guide (link at bottom of each posting to R-help).

Berend