Hello Jonathan,
there are two solutions:
1) Implement the terminal hook function. This hook function is called at
regular intervals by the solver. In the hook function call
glp_error("%s\n", "Aborting due to user request");
Implement the error_hook function to gracefully catch the produced error.
The following code snippets are taken from GLPK for Java:
jmp_buf glp_java_env;
glp_java_callback_env[glp_java_callback_level] = &glp_java_env;
if (setjmp(glp_java_env)) {
glp_java_throw(jenv, "function glp_simplex failed");
} else {
glp_error_hook(glp_java_error_hook, &glp_java_env);
result = (int)glp_simplex(arg1,(glp_smcp const *)arg2);;
}
glp_java_callback_env[glp_java_callback_level] = NULL;
glp_error_hook(NULL, NULL);
/**
* This hook function will be processed if an error occured
* calling the glpk library
* @param in pointer to long jump environment
*/
void glp_java_error_hook(void *in) {
glp_java_error_occured = 1;
/* free GLPK memory */
glp_free_env();
/* safely return */
longjmp(*((jmp_buf*)in), 1);
}
2) If you are solving a MIP problem, and want to get the best solution
yet found, implement a callback routine the address of which you pass
with the iocp structure. In the callback routine call
glp_ios_terminate(tree);
Both has been implemented successfully in example/java/GmplSwing.java of
GLPK for Java.
You can download GLPK for Java from
http://glpk-java.sourceforge.net
It is included in GLPK for Windows available at
http://winglpk.sourceforge.net
Best regards
Xypron
On 24.08.2011 14:25, Andrew Makhorin wrote:
-------- Forwarded Message --------
Subject: Terminating GLPK early
Date: Wed, 24 Aug 2011 12:34:40 +1200
Dear Andrew,
I am currently modifying the GLPKMEX interface to GLPK (Matlab
interface) and wish to be able to terminate a call to GLPK if a user was
to say push Ctrl-C, and return the current best solution. I have read
through the documentation and have tried glp_error() however this also
causes Matlab to crash (not sure if I have done something wrong), but
wondered if there was a cleaner way?
I am imagining an event handler which could be passed to GLPK before
glp_simplex() or another solver is called, which is then called by the
solver each iteration (with perhaps some runtime information), and a
return code passed back to indicate whether to continue or stop.
I apologize if this already exists in GLPK however I have been unable to
find it!
Kind Regards,
Jonathan Currie
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