[Lemon-commits] [lemon_svn] athos: r1757 - hugo/trunk/src/work/athos/lp

[Lemon SVN]

Author: athos
Date: Thu Apr  7 14:54:35 2005
New Revision: 1757

Modified:
   hugo/trunk/src/work/athos/lp/lp_sample.cc

Log:
Sample file completed: works correctly and the code is very beautiful. I love LEMON.

Modified: hugo/trunk/src/work/athos/lp/lp_sample.cc
==============================================================================
--- hugo/trunk/src/work/athos/lp/lp_sample.cc	(original)
+++ hugo/trunk/src/work/athos/lp/lp_sample.cc	Thu Apr  7 14:54:35 2005
@@ -1,15 +1,48 @@
-//#include <stdio.h>
-//#include <stdlib.h>
 #include <iostream>
 #include <lemon/lp_glpk.h>
 using namespace lemon;
 
 int main()
 {     
+ //The following example is taken from the documentation of the GLPK library.
+ //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
   LpGlpk lp;
   typedef LpGlpk::Row Row;
   typedef LpGlpk::Col Col;
-  //std::cout << "Hello" << std::endl;
+
+  lp.max();
+
+  Col x1 = lp.addCol();
+  Col x2 = lp.addCol();
+  Col x3 = lp.addCol();
+
+  //One solution
+  //   Row p = lp.addRow();
+  //   Row q = lp.addRow();
+  //   Row r = lp.addRow();
+  //   lp.setRow(p,x1+x2+x3 <=100);  
+  //   lp.setRow(q,10*x1+4*x2+5*x3<=600);  
+  //   lp.setRow(r,2*x1+2*x2+6*x3<=300);  
+
+  //A more elegant one
+  //Constraints
+  lp.addRow(x1+x2+x3 <=100);  
+  lp.addRow(10*x1+4*x2+5*x3<=600);  
+  lp.addRow(2*x1+2*x2+6*x3<=300);  
+  //Nonnegativity of the variables
+  lp.colLowerBound(x1, 0);
+  lp.colLowerBound(x2, 0);
+  lp.colLowerBound(x3, 0);
+  //Objective function
+  lp.setObj(10*x1+6*x2+4*x3);
+  
+  lp.solve();
+  
+  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", 
+	 lp.primalValue(), 
+	 lp.primal(x1), lp.primal(x2), lp.primal(x3));
+
+  //Here comes the same problem written in C using GLPK API routines
 
 //   LPX *lp;
 //       int ia[1+1000], ja[1+1000];
@@ -17,29 +50,16 @@
 // s1:   lp = lpx_create_prob();
 // s2:   lpx_set_prob_name(lp, "sample");
 // s3:   lpx_set_obj_dir(lp, LPX_MAX);
-  lp.max();
 // s4:   lpx_add_rows(lp, 3);
 // s5:   lpx_set_row_name(lp, 1, "p");
 // s6:   lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
-
-//  Row p = lp.addRow();
-
 // s7:   lpx_set_row_name(lp, 2, "q");
 // s8:   lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
-
-//  Row q = lp.addRow();
-
 // s9:   lpx_set_row_name(lp, 3, "r");
 // s10:  lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
-
-//  Row r = lp.addRow();
-
 // s11:  lpx_add_cols(lp, 3);
 // s12:  lpx_set_col_name(lp, 1, "x1");
 // s13:  lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
-
-//  Col x1 = lp.addCol();
-
 // s14:  lpx_set_obj_coef(lp, 1, 10.0);
 // s15:  lpx_set_col_name(lp, 2, "x2");
 // s16:  lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
@@ -65,5 +85,6 @@
 // s36:  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
 // s37:  lpx_delete_prob(lp);
 //       return 0;
+
   return 0;
 }