[Coin-lpsolver] Using Clp Executable

[John J Forrest]

MPS format gives names to RHS - so you have given three RHS b1,b2 and b3. 
Default will take first so rhs of r2,r3 are zero so optimal solution is 
0.0.

Changing b2 and b3 to b1 should fix problem.

John Forrest



Math407 Summer05 <m407s05 at u.washington.edu> 
Sent by: coin-lpsolver-bounces at list.coin-or.org
06/17/2005 06:20 PM

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Subject
[Coin-lpsolver] Using Clp Executable







I am having trouble using the Clp executable both directly and through 
Neos. Below you will find an e-mail message that I sent Neos followed by 
the Clp results as relayed by Neos. The problem I am trying to solve and 
the solution are listed in the comments in the e-mail sent to Neos. Here 
are my questions:

1. Is my MPS input file correct (given the problem I am trying to solve). 
If not, what have I done wrong ?

2. What is the meaning of the solution output generated by Clp and where 
is this documented ?


%%%%%%%%%%%%%%%% E-mail sent to Neos %%%%%%%%%%%%%%%%%%%%%%%%%%
type lp
solver clp-mps
BEGIN.COMMENT
Example 2.4.3 in Paul Tseng's notes Math 407: Linear Optimization
maximize    x1   +      x2
subject to  x1   +  1.5*x2 <= 30
             2*x1 +      x2 <= 40
                         x2 <= 14
               x1 ,      x2 >= 0

The solution is x1 = 15, x2 = 10
END.COMMENT
begin.mps
*Ke Name0---  Name1---  Value1------
*23 56789012  56789012  567890123456
NAME           T-2.4.3
ROWS
  N         z
  L        r1
  L        r2
  L        r3
COLUMNS
           x1         z            1.
           x1        r1            1.
           x1        r2            2.
*
           x2         z            1.
           x2        r1            1.5
           x2        r2            1.
           x2        r3            1.
RHS
           b1        r1           30.
           b2        r2           40.
           b3        r3           14.
ENDATA
end.mps

BEGIN.PAR
maximize
primalSimplex
solution -
END.PAR
%%%%%%%%%%%%%%%% E-mail sent to Neos %%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%% CLP Results %%%%%%%%%%%%%%%%%%%%

Load Avg: ( 0.0 , 0.0 , 0.0 )
Coin LP version 1.00.01, build Oct 18 2004
At line 3 NAME           T-2.4.3
At line 4 ROWS
At line 9 COLUMNS
At line 18 RHS
At line 22 ENDATA
Problem T-2.4.3 has 3 rows, 2 columns and 5 elements
Model was imported from ./clp.mps in 0 seconds
Switching to line mode
Clp:Clp:Presolve 0 (-3) rows, 0 (-2) columns and 0 (-5) elements
Empty problem - 0 rows, 0 columns and 0 elements
Optimal - objective value 0
After Postsolve, objective -0, infeasibilities - dual 0 (0), primal 0 (0)
Optimal objective -0 - 0 iterations time 0.002, Presolve 0.00
Clp:      0 r1                    0                     -0
       1 r2                    0                    0.5
       2 r3                    0                    0.5
       0 x1                    0                      0
       1 x2                    0                      0
Clp:

%%%%%%%%%%%%%%%%%%%% CLP Results %%%%%%%%%%%%%%%%%%%%
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