1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/demo/lp_demo.cc Fri Apr 15 21:15:30 2005 +0000
1.3 @@ -0,0 +1,96 @@
1.4 +#include <iostream>
1.5 +#include <lemon/lp_glpk.h>
1.6 +using namespace lemon;
1.7 +
1.8 +int main()
1.9 +{
1.10 + //The following example is taken from the documentation of the GLPK library.
1.11 + //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
1.12 + LpGlpk lp;
1.13 + typedef LpGlpk::Row Row;
1.14 + typedef LpGlpk::Col Col;
1.15 +
1.16 + lp.max();
1.17 +
1.18 + Col x1 = lp.addCol();
1.19 + Col x2 = lp.addCol();
1.20 + Col x3 = lp.addCol();
1.21 +
1.22 + //One solution
1.23 + // Row p = lp.addRow();
1.24 + // Row q = lp.addRow();
1.25 + // Row r = lp.addRow();
1.26 + // lp.setRow(p,x1+x2+x3 <=100);
1.27 + // lp.setRow(q,10*x1+4*x2+5*x3<=600);
1.28 + // lp.setRow(r,2*x1+2*x2+6*x3<=300);
1.29 +
1.30 + //A more elegant one
1.31 + //Constraints
1.32 + lp.addRow(x1+x2+x3 <=100);
1.33 + lp.addRow(10*x1+4*x2+5*x3<=600);
1.34 + lp.addRow(2*x1+2*x2+6*x3<=300);
1.35 + //Nonnegativity of the variables
1.36 + lp.colLowerBound(x1, 0);
1.37 + lp.colLowerBound(x2, 0);
1.38 + lp.colLowerBound(x3, 0);
1.39 + //Objective function
1.40 + lp.setObj(10*x1+6*x2+4*x3);
1.41 +
1.42 + lp.solve();
1.43 +
1.44 + if (lp.primalStatus()==LpSolverBase::OPTIMAL){
1.45 + printf("Z = %g; x1 = %g; x2 = %g; x3 = %g\n",
1.46 + lp.primalValue(),
1.47 + lp.primal(x1), lp.primal(x2), lp.primal(x3));
1.48 + }
1.49 + else{
1.50 + std::cout<<"Optimal solution not found!"<<std::endl;
1.51 + }
1.52 +
1.53 +
1.54 + //Here comes the same problem written in C using GLPK API routines
1.55 +
1.56 +// LPX *lp;
1.57 +// int ia[1+1000], ja[1+1000];
1.58 +// double ar[1+1000], Z, x1, x2, x3;
1.59 +// s1: lp = lpx_create_prob();
1.60 +// s2: lpx_set_prob_name(lp, "sample");
1.61 +// s3: lpx_set_obj_dir(lp, LPX_MAX);
1.62 +// s4: lpx_add_rows(lp, 3);
1.63 +// s5: lpx_set_row_name(lp, 1, "p");
1.64 +// s6: lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
1.65 +// s7: lpx_set_row_name(lp, 2, "q");
1.66 +// s8: lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
1.67 +// s9: lpx_set_row_name(lp, 3, "r");
1.68 +// s10: lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
1.69 +// s11: lpx_add_cols(lp, 3);
1.70 +// s12: lpx_set_col_name(lp, 1, "x1");
1.71 +// s13: lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
1.72 +// s14: lpx_set_obj_coef(lp, 1, 10.0);
1.73 +// s15: lpx_set_col_name(lp, 2, "x2");
1.74 +// s16: lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
1.75 +// s17: lpx_set_obj_coef(lp, 2, 6.0);
1.76 +// s18: lpx_set_col_name(lp, 3, "x3");
1.77 +// s19: lpx_set_col_bnds(lp, 3, LPX_LO, 0.0, 0.0);
1.78 +// s20: lpx_set_obj_coef(lp, 3, 4.0);
1.79 +// s21: ia[1] = 1, ja[1] = 1, ar[1] = 1.0; /* a[1,1] = 1 */
1.80 +// s22: ia[2] = 1, ja[2] = 2, ar[2] = 1.0; /* a[1,2] = 1 */
1.81 +// s23: ia[3] = 1, ja[3] = 3, ar[3] = 1.0; /* a[1,3] = 1 */
1.82 +// s24: ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
1.83 +// s25: ia[5] = 3, ja[5] = 1, ar[5] = 2.0; /* a[3,1] = 2 */
1.84 +// s26: ia[6] = 2, ja[6] = 2, ar[6] = 4.0; /* a[2,2] = 4 */
1.85 +// s27: ia[7] = 3, ja[7] = 2, ar[7] = 2.0; /* a[3,2] = 2 */
1.86 +// s28: ia[8] = 2, ja[8] = 3, ar[8] = 5.0; /* a[2,3] = 5 */
1.87 +// s29: ia[9] = 3, ja[9] = 3, ar[9] = 6.0; /* a[3,3] = 6 */
1.88 +// s30: lpx_load_matrix(lp, 9, ia, ja, ar);
1.89 +// s31: lpx_simplex(lp);
1.90 +// s32: Z = lpx_get_obj_val(lp);
1.91 +// s33: x1 = lpx_get_col_prim(lp, 1);
1.92 +// s34: x2 = lpx_get_col_prim(lp, 2);
1.93 +// s35: x3 = lpx_get_col_prim(lp, 3);
1.94 +// s36: printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
1.95 +// s37: lpx_delete_prob(lp);
1.96 +// return 0;
1.97 +
1.98 + return 0;
1.99 +}