[ADMB Users] Non-matching analytic and numeric derivatives
davef at otter-rsch.com
Tue Oct 21 06:58:49 PDT 2014
A few issues.
I did not intend to present a "final solution" to your
What I did intend to do was to illustrate how overall
stability of the model could be improved by modifying
the objective function in phases. Then I hoped that
you and others could incorporate the techniques into
their bag of tricks. So for example one could use 3
phases and add an even smaller offset in the third phase.
As for buffer sizes there are two issues. One is
specifying the offset into a >2GB buffer. That has
to be a type > 32 bits. In 64 bit windows it seems that
a long int is only 32 bits and mingw64 has followed this
for windows compatibility. A long long int will do the
job but there are other types which can be used. I always
forget what they are.
Then there is the question of writing the buffer to the
disk when it is full. I used a low level unbuffered
write function, assuming at the time that it would be
the fastest method. However the amount that can be
written in one write operation is limited. On my Linux
system it appears to be 2GB. So one can either split up
the write operations or switch to higher level fwrites.
For the model in question here I used a buffer > 3.5 GB
which was large enough that nothing needed to be written
to the disk. This works because in 64 bit Linux a long
int is 64 bits.
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