[Ipopt] Question about largest Jacobian

Panos Lambrianides panos at soe.ucsc.edu
Mon Jun 8 14:13:02 EDT 2015

Yes thank you my mistake.  That is more than adequate for my needs.  It
just struck me as a little odd why anyone would use an int for large scale

Many thanks for the responses.


On Mon, Jun 8, 2015 at 11:07 AM, Stefan Vigerske <stefan at math.hu-berlin.de>

> Hi,
> On 06/08/2015 07:51 PM, Panos Lambrianides wrote:
>> Hi everyone,
>> I have a question about the largest size of the Jacobian for the
>> constraints.
>> While setting up the problem the variable nnz_jac_g is used to set up the
>> number of non-zero constraint for the Jacobian.  This is of type *Index*,
>> which is itself an *int* in C++.  The upper limit for int is 32767
>> (2^15-1).
> I believe that int's are 32bit, so you get an upper limit of around
> 2147483647.
>  Is there a reason why this is an int (versus a long for example) and more
>> importantly is there a way to overcome this limitation?  I would be happy
>> to tweak the code if someone would point out the right places to do so.
> There are some feature requests on this:
> https://projects.coin-or.org/Ipopt/ticket/251
> https://projects.coin-or.org/Ipopt/ticket/259
> The main thing to do is to extend a number of interfaces to 3rd-party
> software (linear algebra and linear solvers) to convert Ipopt's
> Index-arrays to their int-arrays, when necessary (or convince them to use
> also a long for indices).
> Stefan

Panos Lambrianides
panos at soe.ucsc.edu
(415) 713-6718 (Mobile)
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