MixedIntegerLinearProgram/MIPVariable: set_min, set_max are broken

[mkoeppe]

Here's a bug:

sage: p.<x,y> = MixedIntegerLinearProgram()
sage: x[0], y[0]
(x_0, x_1)
sage: p.set_max(x, 42)
sage: p.get_max(y[0])
42.0

The bug is in MIPVariable.set_min, .set_max, which calls back into the problem to change the bounds of all variables of the problem rather than just its components.

CC: @dimpase @videlec @jdemeyer @fchapoton @nbruin

Component: numerical

Author: Matthias Koeppe

Branch/Commit: 3a8b10d

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/20462

[mkoeppe]

Description changed:

--- 
+++ 
@@ -13,6 +13,8 @@
 Oh, and why does a `MIPVariable` only have `set_max`, but no `get_max`? 
 And why all of that bizarre delegating to `MIPVariable` when other `MixedIntegerLinearProgram` methods such as `set_integer` etc. just do everything directly, and no corresponding `MIPVariable` methods exist?
 
+I guess this is also a great moment to mention that these things should properly be referred to as `lower_bound` and `upper_bound` rather than `min` and `max`. Some deprecation fun to be had.
+
 And why is there no way to query the values of the components of the `_default_mipvariable`?
 
 

[mkoeppe]

Description changed:

--- 
+++ 
@@ -10,11 +10,4 @@
 ```
 The bug is in `MIPVariable.set_min`, `.set_max`, which calls back into the problem to change the bounds of *all* variables of the problem rather than just its components. 
 
-Oh, and why does a `MIPVariable` only have `set_max`, but no `get_max`? 
-And why all of that bizarre delegating to `MIPVariable` when other `MixedIntegerLinearProgram` methods such as `set_integer` etc. just do everything directly, and no corresponding `MIPVariable` methods exist?
 
-I guess this is also a great moment to mention that these things should properly be referred to as `lower_bound` and `upper_bound` rather than `min` and `max`. Some deprecation fun to be had.
-
-And why is there no way to query the values of the components of the `_default_mipvariable`?
-
-

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Branch: u/mkoeppe/mixedintegerlinearprogram_mipvariable__get_min__set_min__get_max__set_max_are_broken

[mkoeppe]

Commit: 3a8b10d

[mkoeppe]

New commits:

3a8b10d

Fix #20462 - MIPVariable.set_min, set_max

[tscrim]

comment:8

LGTM.

[tscrim]

Reviewer: Travis Scrimshaw