Re: [Help-glpk] Can I use API to form non-standard LP problem?

[xypron]

Hello,

the API allows to create the LP problem in your example.

I would suggest you first bring you problem into the normal form:
- constant term on the right hand side
- variable terms on the left hand side.

Then you may create the problem row by row or column by column.

To create the problem row by row, start with creating the problem:
glp_create_prob
glp_set_prob_name

Create the columns (variables)
glp_add_cols
glp_set_col_name
glp_set_col_kind
glp_set_col_bnds

Create the rows (constraints)
glp_add_rows
glp_set_row_name
glp_set_row_bnds
glp_set_mat_row

Create the objective
glp_set_obj_name
glp_set_obj_dir
glp_set_obj_coef

Start the solver
glp_init_smcp
glp_simplex

Retrieve the result
glp_get_num_cols
glp_get_col_name
glp_get_col_prim

Delete the problem
glp_delete_prob

You can find a Java example here:
http://www.nabble.com/file/p22711936/GLPKtest001.java GLPKtest001.java 

Best regards

Xypron



rainly wrote:
> 
> Hello,I am new to the glpk package and i needed some help:
> I have an objective function and a set of constraints
> but I dont know how to pogram it with glpk.I want to
> use the set of api routines the glpk provides.
> I have read the example in the manual but
> still the example is so simple compared to my
> equations. Following is just a very small example and I know how to write
> an
> input file to solve the problem. Please let me know if I can do it
> using API.
> 
> objective function
> min : a1+a2+a3+a4+a5+a6+2.5 b1+2.5 b2+2.5 b3+ 2.5
> b4+2.5 b5+2.5 b6
> 
> Constraints:
> 
> x_1_1 + x_1_2 +x_1_3 = 151;
> x_2_1 + x_2_2 +x_2_3 = 401;
> x_3_1 + x_3_2 +x_3_3 = 51;
> x_4_1 + x_4_2 +x_4_3 = 101;
> x_5_1 + x_5_2 +x_5_3 = 51;
> x_6_1 + x_6_2 +x_6_3 = 31;
> 
> x_1_1 + x_2_2 + x_3_2+x_4_2+x_5_2 <= 63 a1+252 b1
> x_1_2 + x_2_1 + x_3_3+x_4_2+x_6_2 <= 63 a2+252 b2
> x_1_3 + x_2_3 + x_3_1+x_5_2+x_6_2 <= 63 a3+252 b3
> x_1_2 + x_2_2 + x_4_1+x_5_3+x_6_3 <= 63 a4+252 b4
> x_1_3 + x_3_2 + x_4_3+x_5_1+x_6_3 <= 63 a5+252 b5
> x_2_3 + x_3_3 + x_4_3+x_5_3+x_6_1 <= 63 a6+252 b6
> 
> Thanks in advance,
> 

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