/*------------------------------------------------------------------------*/
/* File: examples/src/lpex5.c */
/* Version 8.1 */
/*------------------------------------------------------------------------*/
/* Copyright (C) 1997-2002 by ILOG. */
/* All Rights Reserved. */
/* Permission is expressly granted to use this example in the */
/* course of developing applications that use ILOG products. */
/*------------------------------------------------------------------------*/
/* lpex5.c - Illustrating the CPLEX message handler
This is a modification of lpex1.c .
We'll label each channels output with its name, and
also put our own output into a file. Note that the labels
may cause the output to go past 80 characters per line. */
/* Bring in the CPLEX function declarations and the C library
header file stdio.h with the following single include. */
#include <ilcplex/cplex.h>
/* Bring in the declarations for the string functions */
#include <string.h>
/* Include declaration for function at end of program */
static int
populatebycolumn (CPXENVptr env, CPXLPptr lp);
static void CPXPUBLIC
ourmsgfunc (void *handle, const char *message);
/* The problem we are optimizing will have 2 rows, 3 columns
and 6 nonzeros. */
#define NUMROWS 2
#define NUMCOLS 3
#define NUMNZ 6
int
main (void)
{
char probname[16]; /* Problem name is max 16 characters */
/* Declare and allocate space for the variables and arrays where we
will store the optimization results including the status, objective
value, variable values, dual values, row slacks and variable
reduced costs. */
int solstat;
double objval;
double x[NUMCOLS];
double pi[NUMROWS];
double slack[NUMROWS];
double dj[NUMCOLS];
CPXENVptr env = NULL;
CPXLPptr lp = NULL;
int status;
int i, j;
int cur_numrows, cur_numcols;
char errmsg[1024];
CPXCHANNELptr cpxerror = NULL;
CPXCHANNELptr cpxwarning = NULL;
CPXCHANNELptr cpxresults = NULL;
CPXCHANNELptr ourchannel = NULL;
char *errorlabel = "cpxerror";
char *warnlabel = "cpxwarning";
char *reslabel = "cpxresults";
char *ourlabel = "Our Channel";
CPXFILEptr fpout = NULL;
/* Initialize the CPLEX environment */
env = CPXopenCPLEX (&status);
/* If an error occurs, the status value indicates the reason for
failure. A call to CPXgeterrorstring will produce the text of
the error message. Note that CPXopenCPLEX produces no output,
so the only way to see the cause of the error is to use
CPXgeterrorstring. For other CPLEX routines, the errors will
be seen if the CPX_PARAM_SCRIND indicator is set to CPX_ON. */
/* Since the message handler is yet to be set up, we'll call our
messaging function directly to print out any errors */
if ( env == NULL ) {
/* The message argument for ourmsgfunc must not be a constant,
so copy the mesage to a buffer. */
strcpy (errmsg, "Could not open CPLEX environment.\n");
ourmsgfunc ("Our Message", errmsg);
goto TERMINATE;
}
/* Now get the standard channels. If an error, just call our
message function directly. */
status = CPXgetchannels (env, &cpxresults, &cpxwarning, &cpxerror, NULL);
if ( status ) {
strcpy (errmsg, "Could not get standard channels.\n");
ourmsgfunc ("Our Message", errmsg);
CPXgeterrorstring (env, status, errmsg);
ourmsgfunc ("Our Message", errmsg);
goto TERMINATE;
}
/* Now set up the error channel first. The label will be "cpxerror" */
status = CPXaddfuncdest (env, cpxerror, errorlabel, ourmsgfunc);
if ( status ) {
strcpy (errmsg, "Could not set up error message handler.\n");
ourmsgfunc ("Our Message", errmsg);
CPXgeterrorstring (env, status, errmsg);
ourmsgfunc ("Our Message", errmsg);
}
/* Now that we have the error message handler set up, all CPLEX
generated errors will go through ourmsgfunc. So we don't have
to use CPXgeterrorstring to determine the text of the message.
We can also use CPXmsg to do any other printing. */
status = CPXaddfuncdest (env, cpxwarning, warnlabel, ourmsgfunc);
if ( status ) {
CPXmsg (cpxerror, "Failed to set up handler for cpxwarning.\n");
goto TERMINATE;
}
status = CPXaddfuncdest (env, cpxresults, reslabel, ourmsgfunc);
if ( status ) {
CPXmsg (cpxerror, "Failed to set up handler for cpxresults.\n");
goto TERMINATE;
}
/* Now turn on the iteration display. */
status = CPXsetintparam (env, CPX_PARAM_SIMDISPLAY, 2);
if ( status ) {
CPXmsg (cpxerror, "Failed to turn on simplex display level.\n");
goto TERMINATE;
}
/* Create the problem. */
strcpy (probname, "example");
lp = CPXcreateprob (env, &status, probname);
/* A returned pointer of NULL may mean that not enough memory
was available or there was some other problem. In the case of
failure, an error message will have been written to the error
channel from inside CPLEX. In this example, the setting of
the parameter CPX_PARAM_SCRIND causes the error message to
appear on stdout. */
if ( lp == NULL ) {
CPXmsg (cpxerror, "Failed to create LP.\n");
goto TERMINATE;
}
/* Now populate the problem with the data. */
status = populatebycolumn (env, lp);
if ( status ) {
CPXmsg (cpxerror, "Failed to populate problem data.\n");
goto TERMINATE;
}
/* Optimize the problem and obtain solution. */
status = CPXlpopt (env, lp);
if ( status ) {
CPXmsg (cpxerror, "Failed to optimize LP.\n");
goto TERMINATE;
}
status = CPXsolution (env, lp, &solstat, &objval, x, pi, slack, dj);
if ( status ) {
CPXmsg (cpxerror, "Failed to obtain solution.\n");
goto TERMINATE;
}
/* Write the output to the screen. We will also write it to a
file as well by setting up a file destination and a function
destination. */
ourchannel = CPXaddchannel (env);
if ( ourchannel == NULL ) {
CPXmsg (cpxerror, "Failed to set up our private channel.\n");
goto TERMINATE;
}
fpout = CPXfopen ("lpex5.msg", "w");
if ( fpout == NULL ) {
CPXmsg (cpxerror, "Failed to open lpex5.msg file for output.\n");
goto TERMINATE;
}
status = CPXaddfpdest (env, ourchannel, fpout);
if ( status ) {
CPXmsg (cpxerror, "Failed to set up output file destination.\n");
goto TERMINATE;
}
status = CPXaddfuncdest (env, ourchannel, ourlabel, ourmsgfunc);
if ( status ) {
CPXmsg (cpxerror, "Failed to set up our output function.\n");
goto TERMINATE;
}
/* Now any message to channel ourchannel will go into the file
and into the file opened above. */
CPXmsg (ourchannel, "\nSolution status = %d\n", solstat);
CPXmsg (ourchannel, "Solution value = %f\n\n", objval);
/* The size of the problem should be obtained by asking CPLEX what
the actual size is, rather than using sizes from when the problem
was built. cur_numrows and cur_numcols store the current number
of rows and columns, respectively. */
cur_numrows = CPXgetnumrows (env, lp);
cur_numcols = CPXgetnumcols (env, lp);
for (i = 0; i < cur_numrows; i++) {
CPXmsg (ourchannel, "Row %d: Slack = %10f Pi = %10f\n",
i, slack[i], pi[i]);
}
for (j = 0; j < cur_numcols; j++) {
CPXmsg (ourchannel, "Column %d: Value = %10f Reduced cost = %10f\n",
j, x[j], dj[j]);
}
/* Finally, write a copy of the problem to a file. */
status = CPXwriteprob (env, lp, "lpex5.lp", NULL);
if ( status ) {
CPXmsg (cpxerror, "Failed to write LP to disk.\n");
goto TERMINATE;
}
TERMINATE:
/* First check if ourchannel is open */
if ( ourchannel != NULL ) {
int chanstat;
chanstat = CPXdelfuncdest (env, ourchannel, ourlabel, ourmsgfunc);
if ( chanstat ) {
strcpy (errmsg, "CPXdelfuncdest failed.\n");
ourmsgfunc ("Our Message", errmsg);
if (!status) status = chanstat;
}
if ( fpout != NULL ) {
chanstat = CPXdelfpdest (env, ourchannel, fpout);
if ( chanstat ) {
strcpy (errmsg, "CPXdelfpdest failed.\n");
ourmsgfunc ("Our Message", errmsg);
if (!status) status = chanstat;
}
CPXfclose (fpout);
}
CPXdelchannel (env, &ourchannel);
}
/* Free up the problem as allocated by CPXcreateprob, if necessary */
if ( lp != NULL ) {
status = CPXfreeprob (env, &lp);
if ( status ) {
strcpy (errmsg, "CPXfreeprob failed.\n");
ourmsgfunc ("Our Message", errmsg);
}
}
/* Now delete our function destinations from the 3 CPLEX channels. */
if ( cpxresults != NULL ) {
int chanstat;
chanstat = CPXdelfuncdest (env, cpxresults, reslabel, ourmsgfunc);
if ( chanstat && !status ) {
status = chanstat;
strcpy (errmsg, "Failed to delete cpxresults function.\n");
ourmsgfunc ("Our Message", errmsg);
}
}
if ( cpxwarning != NULL ) {
int chanstat;
chanstat = CPXdelfuncdest (env, cpxwarning, warnlabel, ourmsgfunc);
if ( chanstat && !status ) {
status = chanstat;
strcpy (errmsg, "Failed to delete cpxwarning function.\n");
ourmsgfunc ("Our Message", errmsg);
}
}
if ( cpxerror != NULL ) {
int chanstat;
chanstat = CPXdelfuncdest (env, cpxerror, errorlabel, ourmsgfunc);
if ( chanstat && !status ) {
status = chanstat;
strcpy (errmsg, "Failed to delete cpxerror function.\n");
ourmsgfunc ("Our Message", errmsg);
}
}
/* Free up the CPLEX environment, if necessary */
if ( env != NULL ) {
status = CPXcloseCPLEX (&env);
/* Note that CPXcloseCPLEX produces no output,
so the only way to see the cause of the error is to use
CPXgeterrorstring. For other CPLEX routines, the errors will
be seen if the CPX_PARAM_SCRIND indicator is set to CPX_ON. */
if ( status ) {
strcpy (errmsg, "Could not close CPLEX environment.\n");
ourmsgfunc ("Our Message", errmsg);
CPXgeterrorstring (env, status, errmsg);
ourmsgfunc ("Our Message", errmsg);
}
}
return (status);
} /* END main */
/* This function builds by column the linear program:
Maximize
obj: x1 + 2 x2 + 3 x3
Subject To
c1: - x1 + x2 + x3 <= 20
c2: x1 - 3 x2 + x3 <= 30
Bounds
0 <= x1 <= 40
End
*/
static int
populatebycolumn (CPXENVptr env, CPXLPptr lp)
{
int status = 0;
double obj[NUMCOLS];
double lb[NUMCOLS];
double ub[NUMCOLS];
char *colname[NUMCOLS];
int matbeg[NUMCOLS];
int matind[NUMNZ];
double matval[NUMNZ];
double rhs[NUMROWS];
char sense[NUMROWS];
char *rowname[NUMROWS];
/* To build the problem by column, create the rows, and then
add the columns. */
CPXchgobjsen (env, lp, CPX_MAX); /* Problem is maximization */
/* Now create the new rows. First, populate the arrays. */
rowname[0] = "c1";
sense[0] = 'L';
rhs[0] = 20.0;
rowname[1] = "c2";
sense[1] = 'L';
rhs[1] = 30.0;
status = CPXnewrows (env, lp, NUMROWS, rhs, sense, NULL, rowname);
if ( status ) goto TERMINATE;
/* Now add the new columns. First, populate the arrays. */
obj[0] = 1.0; obj[1] = 2.0; obj[2] = 3.0;
matbeg[0] = 0; matbeg[1] = 2; matbeg[2] = 4;
matind[0] = 0; matind[2] = 0; matind[4] = 0;
matval[0] = -1.0; matval[2] = 1.0; matval[4] = 1.0;
matind[1] = 1; matind[3] = 1; matind[5] = 1;
matval[1] = 1.0; matval[3] = -3.0; matval[5] = 1.0;
lb[0] = 0.0; lb[1] = 0.0; lb[2] = 0.0;
ub[0] = 40.0; ub[1] = CPX_INFBOUND; ub[2] = CPX_INFBOUND;
colname[0] = "x1"; colname[1] = "x2"; colname[2] = "x3";
status = CPXaddcols (env, lp, NUMCOLS, NUMNZ, obj, matbeg, matind,
matval, lb, ub, colname);
if ( status ) goto TERMINATE;
TERMINATE:
return (status);
} /* END populatebycolumn */
/* For our message functions, we will interpret the handle as a pointer
* to a string, which will be the label for the channel. We'll put
* angle brackets <> around the message so its clear what the function is
* sending to us. We'll place the newlines that appear at the end of
* a message after the > bracket. The 'message' argument must not be
* a constant, since it is changed by this function.
*/
static void CPXPUBLIC
ourmsgfunc (void *handle, const char *msg)
{
char *label;
int lenstr;
int flag = 0;
char *message = (char *)msg;
lenstr = strlen(message);
if ( message[lenstr-1] == '\n' ) {
message[lenstr-1] = '\0';
flag = 1;
}
label = (char *) handle;
printf ("%-15s: <%s>", label, message);
if (flag) putchar('\n');
/* If we clobbered the '\n', we need to put it back */
if ( flag ) message[lenstr-1] = '\n';
} /* END ourmsgfunc */
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