[Bonmin] bonmin and ipopt

[Roy Chen]

Hello everyone

I tried the following problem:

function Integral1(Reals,Reals,Reals);
var x ;
var y ;
minimize Z:tan(x)+y*Integral1(x,0,1);
subject to constrain:x+y>=5;
subject to constraint:2*x+3*y<=27;
option solver ipopt;
solve;
display x;
display y;
display Z;

When the solver option was chosen "ipopt" as above, I got the following
solution:
EXIT: Optimal Solution Found.
Ipopt 3.2.2: Optimal Solution Found
x = -12
y = 17
Z = 7.41788
When the solver option was chosen "bonmin" and every parameter in bonmin
remains default, I got the following:

bonmin:
******************************************************************************
This program contains Ipopt, a library for large-scale nonlinear
optimization.
 Ipopt is released as open source code under the Common Public License
(CPL).
         For more information visit http://projects.coin-or.org/Ipopt
******************************************************************************

Ipopt exited with error code -2 Restoration Failed
Error in opening Names file (probably does not exists)can't open
/tmp/at2970.sol

Note: Integral1() is the external function I defined by myself. Actually I
tried all of the four algorithms in bonmin, one of them works.

Why the two outputs are so different? Anyone has some idea?

Thanks
Roy
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