[Octave-bug-tracker] [bug #55905] ode15{i, s} allocate enough memory for a full jacobian when the provided jacobian is sparse

[Carlo de Falco]

URL:
  <https://savannah.gnu.org/bugs/?55905>

                 Summary: ode15{i,s} allocate enough memory for a full
jacobian when the provided jacobian is sparse 
                 Project: GNU Octave
            Submitted by: cdf
            Submitted on: Wed 13 Mar 2019 09:32:38 AM CET
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Performance
                  Status: In Progress
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

The memory allocation for the sparse jacobian 
is done in an overly safe way here
<http://hg.savannah.gnu.org/hgweb/octave/file/d94876e7a0aa/libinterp/dldfcn/__ode15__.cc#l356>

The memory is allocated as if the jacobian was full.

It would be more memory efficient to check the actual size of the needed
memory before doing the allocation.

I have already added a FIXME comment in the code, I am posting this here as
well in order not to forget.




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