# Computing polyhedron from MIP

I want to run the following code (I'm using SAGE v6.10 release version 2015-12-18):

```
P = MixedIntegerLinearProgram()
x = P.new_variable()
A = random_matrix(RR, 3, 2);
P.add_constraint(A*x <= [2.1,1.5,0.4])
P.polyhedron()
```

However, it outputs the error message:

AttributeError: type object 'float' has no attribute 'fraction_field'

I noticed that if instead of using real variables I use only integer variables, then it works fine. For instance:

```
P = MixedIntegerLinearProgram()
x = P.new_variable()
A = random_matrix(ZZ, 3, 2);
P.add_constraint(A*x <= [2,1,0])
P.polyhedron()
```

outputs:

A 2-dimensional polyhedron in QQ^2 defined as the convex hull of 1 vertex and 2 rays

What do you suggest to overcome this problem?

Thanks

About 2 years ago (not sure which version of Sage that was), the polyhedron worked. But, it appears to be an issue now.

Thanks. Anyway, I should try installing sagemath v7.2.