Re: [Help-glpk] help me!!!

[Andrew Makhorin]

>I am now working on solving the sample.c data  by MIP methods and always
>get a results of "px_integer: optimal solution of LP relaxation
>required"
>
>Can anyone tell me why and how to fix it??

Before using lpx_integer you should obtain an optimal solution of LP
relaxation by means of lpx_simplex. In other word, your program should
look like follows:

   ...
   /* create mip problem instance */
   lp = lpx_create_prob();
   lpx_set_class(lp, LPX_MIP);
   ...
   /* scale the problem (optional) */
   lpx_scale_prob(lp);
   /* construct advanced initial basis (optional) */
   lpx_adv_basis(lp);
   /* find optimal solution of LP relaxation */
   ret = lpx_simplex(lp);
   /* make sure that the simplex method has successfully solved lp */
   assert(ret == LPX_E_OK);
   /* make sure that optimal solution exists */
   assert(lpx_get_status(lp) == LPX_OPT);
   /* try to solve mip using the branch-and-bound method */
   ret = lpx_integer(lp);
   ...