Problem in serialization of matrix variables using [] in minibex

[raphaelchenouard]

With following model:
`
Variables
x[2][2] in [-1,1];

Minimize x[1][1]+x[0][0];
Printing the system (with cout<<sys) results in:variables:
x[2][2]
box:
([-1, 1] ; [-1, 1] ; [-1, 1] ; [-1, 1])
goal:
(x(2,:)(2)+x(1,:)(1))
`
The row index in the goal function is not printed well.
Using parenthesis instead of square brackets prints well.

In fact, current parsing creates a nested ExprIndex in an ExprIndex for the second index. The nested index has no value for the second dimension, that's why the ':' is printed.

Looking at the yacc file for the parser, there is no explicit rule for matrix index with [] (l 297), whereas there is an explicit one for () (l. 299).
Maybe just adding this rule
| expr '[' expr_index ',' expr_index ']' { $$ = expr_with_index($1,$3,$5,false); }
can solve the problem, but maybe it makes the grammar inconsistent due to similar a rule for intervals.

[gchabert]

Thanks for reporting the issue and analyzing it so deep. It has been fixed.
As you guessed, it was not possible to include a simplification rule for this case directly in the parser because of a conflict with the interval definition. But a simplification at higher level (in the system factory) was actually missing for the goal function.