auglag divide by zero

[galbramc]

On line 177 of auglag.c there is:

d.rho = MAX(1e-6, MIN(10, 2 * fabs(*minf) / con2));

However, if there are only inequality constraints and they are all satisfied then con2 == 0. Something like

if (con2 == 0) d.rho = 10;
else d.rho = MAX(1e-6, MIN(10, 2 * fabs(*minf) / con2));

would be a simple fix, but I'm just guessing.

[jschueller]

please provide a simple test-case

[galbramc]

I've attached a modified version of the tutorial that reproduces the divide by zero.
tutorial.txt

[jschueller]

you start from 0, with sqrt ... closing
Please provide a valid test case

[galbramc]

My apologize I put together the example in haste and didn't notice I had the 1/0 in there. I've updated the the example tutorial.txt.

I modified the objective function to remove the 1/0 and provide two initial guesses. One initial guess where the constraint is satisfied and one initial guess where the constraint is violated. I also enabled floating point trapping. Running the example with gdb to catch the floating point exeption I get:

gdb ./a.out
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Reading symbols from ./a.out...done.
(gdb) run
Starting program: /home/galbramc/util/NLOPT/nlopt-2.5.0/test/a.out

Program received signal SIGFPE, Arithmetic exception.
0x0000000000443992 in auglag_minimize (n=2, f=0x4028f6 <myfunc>, f_data=0x0, m=0, fc=0x6b0d90, p=0, h=0x0, lb=0x6b0d10, ub=0x6b0d30, x=0x7fffffffd130,
    minf=0x7fffffffd120, stop=0x7fffffffd000, sub_opt=0x6b0e20, sub_has_fc=0) at /home/galbramc/util/NLOPT/nlopt-2.5.0/src/algs/auglag/auglag.c:177
177               d.rho = MAX(1e-6, MIN(10, 2 * fabs(*minf) / con2));
(gdb) print con2
$1 = 0
(gdb)

Using the initial guess that violates the constraint works just fine because con2 >
0.