Re: [Help-glpk] Operand following / has invalid type
On Thu, 10 Sep 2020, Andrew Makhorin wrote:
On Wed, 2020-09-09 at 18:17 -0300, yami...@cock.li wrote:
I'm trying to make a program that populates a binary matrix keeping
as
many blank lines as possible, e.g.
Add another variable for each row in the binary matrix:
z[row]>=m[row, col]
minimize its sum.
The z's need not be binary.
It can be done with a single z,
but I expect user-defined cuts would be necessary.
Note that GLPK assumes cuts are not mathematically necessary.
GLPK might return a solution you deem infeasible.
In that case, you would neeed to add a cut and rerun.
Keeping the previously discovered cuts would not be automatic.
Since I know the sum of the lines won't be too big I decided to use
an
approach based on division, but I'm getting a "operand following /
has
invalid type" error.
/* binary matrix */
var m{x in X, y in Y} binary;
/* minimizes total (sum of line)^-1, a full line is better than two
half-full lines*/
minimize maxEmpty: sum{x in X} 1/(1 + sum{y in Y} m[x,y]);
This can be done, sort of.
Again you would need an auxillary variable for each matrix row.
I expect the additional constraints
could be inserted with the original set.
Again it coulod be done with a single z
and the same complications are before.
In constraints and objectives you can divide only by a constant
expression. In your case you divide by a linear form that leads to a
non-linear objective function, which is not allowed. Probably you need
to reformulate your model.
--
Michael henne...@web.cs.ndsu.nodak.edu
"Sorry but your password must contain an uppercase letter, a number,
a haiku, a gang sign, a heiroglyph, and the blood of a virgin."
-- someeecards
Re: [Help-glpk] Operand following / has invalid type
On Wed, 2020-09-09 at 18:17 -0300, yami...@cock.li wrote:
> Hey,
>
> I'm trying to make a program that populates a binary matrix keeping
> as
> many blank lines as possible, e.g.
>
> > 00|
> > 11|
> > 10|
>
> instead of
>
> > 10|
> > 10|
> > 10|
>
>
> Since I know the sum of the lines won't be too big I decided to use
> an
> approach based on division, but I'm getting a "operand following /
> has
> invalid type" error.
>
> /* binary matrix */
> var m{x in X, y in Y} binary;
> /* minimizes total (sum of line)^-1, a full line is better than two
> half-full lines*/
> minimize maxEmpty: sum{x in X} 1/(1 + sum{y in Y} m[x,y]);
>
> I made a few tests and some constraints, I'm pretty sure it's not a
> problem with the sets, the matrix, or a typo.
> If I had to guess I'd say the error is being caused by the nested
> sums,
> but I couldn't find much on that.
>
> Can this be fixed in any way?
> Thanks.
>
>
In constraints and objectives you can divide only by a constant
expression. In your case you divide by a linear form that leads to a
non-linear objective function, which is not allowed. Probably you need
to reformulate your model.
[Help-glpk] Operand following / has invalid type
Hey,
I'm trying to make a program that populates a binary matrix keeping as
many blank lines as possible, e.g.
|00|
|11|
|10|
instead of
|10|
|10|
|10|
Since I know the sum of the lines won't be too big I decided to use an
approach based on division, but I'm getting a "operand following / has
invalid type" error.
/* binary matrix */
var m{x in X, y in Y} binary;
/* minimizes total (sum of line)^-1, a full line is better than two
half-full lines*/
minimize maxEmpty: sum{x in X} 1/(1 + sum{y in Y} m[x,y]);
I made a few tests and some constraints, I'm pretty sure it's not a
problem with the sets, the matrix, or a typo.
If I had to guess I'd say the error is being caused by the nested sums,
but I couldn't find much on that.
Can this be fixed in any way?
Thanks.
