[Cmpl] Suboptimal solution when reading from CSV

[Indrajit Sen Gupta]

Hi Mike,

I am trying out one of the examples from the manual (Pg 31):

-------------------------------------------------------------------
%arg -solver cbc
%arg -solutionAscii
parameters:
# Reading data from CSV
 c[] := readcsv("c.csv");
 b[] := readcsv("b.csv");
 A[,] := readcsv("a.csv");
# Reading data directly
# c[] := (1,2,3);
# b[] := (15,20);
# A[,] := ((5.6, 7.7, 10.5),
#   (9.8, 4.2, 11.1));

variables:
 x[defset(c[])] : real[0..];

objectives:
 c[]T * x[] -> max;
constraints:
 A[,] * x[] <= b[];
-------------------------------------------------------------------
When I use the readcsv command to read the data, this is the output that I
get:

---------------------------------------------------------------------------------------------------------
Problem              prob04.cmpl
Nr. of variables     3
Nr. of constraints   2
Objective name       line[1]
Solver name          CBC
Display variables    (all)
Display constraints  (all)
---------------------------------------------------------------------------------------------------------
Objective status     optimal
Objective value      3.8961 (max!)
Variables
Name                 Type            Activity         Lower bound
Upper bound            Marginal
---------------------------------------------------------------------------------------------------------
x[1]                    C                   0
0            Infinity           -0.454545
x[2]                    C             1.94805
0            Infinity                   0
x[3]                    C                   0
0            Infinity           -0.727273
---------------------------------------------------------------------------------------------------------
Constraints
Name                 Type            Activity         Lower bound
Upper bound            Marginal
---------------------------------------------------------------------------------------------------------
line[2]                 L                  15
-Infinity                  15             0.25974
line[3]                 L             8.18182
-Infinity                  20                   0
---------------------------------------------------------------------------------------------------------
This is obviously not optimal. Now if I read the data directly from inside
the CMPL file, I get the correct answer:

---------------------------------------------------------------------------------------------------------
Problem              prob04.cmpl
Nr. of variables     3
Nr. of constraints   2
Objective name       line[1]
Solver name          CBC
Display variables    (all)
Display constraints  (all)
---------------------------------------------------------------------------------------------------------
Objective status     optimal
Objective value      4.28571 (max!)
Variables
Name                 Type            Activity         Lower bound
Upper bound            Marginal
---------------------------------------------------------------------------------------------------------
x[1]                    C                   0
0            Infinity                -0.6
x[2]                    C                   0
0            Infinity                -0.2
x[3]                    C             1.42857
0            Infinity                   0
---------------------------------------------------------------------------------------------------------
Constraints
Name                 Type            Activity         Lower bound
Upper bound            Marginal
---------------------------------------------------------------------------------------------------------
line[2]                 L                  15
-Infinity                  15            0.285714
line[3]                 L             15.8571
-Infinity                  20                   0
---------------------------------------------------------------------------------------------------------
Any thoughts on why this is happening?

The contents of the CSV files are exactly as mentioned in page 31.

Regards,
Indrajit
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