`0 - Var` returns wrong result

vang1ong7ang commented 4 years ago

Describe the bug

0 - Var returns wrong result

To Reproduce Steps to reproduce the behavior please include attached any files needed to reproduce the error. We can only help you if we can reproduce the error ourselves and debug.

from mip import Model

m = Model()

x = m.add_var()
print(x)
y = 0 - x
print(y)

Expected behavior A clear and concise description of what you expected to happen.

expect output should be:

var(0)
- var(0)

but actually it is:

var(0)
var(0)

Desktop (please complete the following information):

Operating System, version: Linux bd351c4cdf15 4.19.125-1.*****.*****.x86_64 #1 SMP Sat May 30 16:11:30 UTC 2020 x86_64 GNU/Linux
Python version: 3.8.1
Python-MIP version (we recommend you to test with the latest version): 1.9.3

Additional context Add any other context about the problem here.

vang1ong7ang commented 4 years ago

the problem should be here:

https://github.com/coin-or/python-mip/blob/a215205607bad484d57a6bc7cba0e3c75e64f3ed/mip/entities.py#L571-L572

tuliotoffolo commented 4 years ago

Thank you very much for pointing this out! I believe the problem is fixed now!

coin-or / python-mip

`0 - Var` returns wrong result #126