Sage Reference Manual: Numerical Optimization - Mirrors

Sage Reference Manual: Numerical Optimization, Release 6.1.1
get_min(v)
Returns the minimum value of a variable.
INPUT:
•v – a variable (not a MIPVariable, but one of its elements).
OUTPUT:
Minimum value of the variable, or None if the variable has no lower bound.
EXAMPLE:
sage: p = MixedIntegerLinearProgram()
sage: v = p.new_variable()
sage: p.set_objective(v[1])
sage: p.get_min(v[1])
0.0
sage: p.set_min(v[1],6)
sage: p.get_min(v[1])
6.0
sage: p.set_min(v[1], None)
sage: p.get_min(v[1])
get_values(*lists)
Return values found by the previous call to solve().
INPUT:
•Any instance of MIPVariable (or one of its elements), or lists of them.
OUTPUT:
•Each instance of MIPVariable is replaced by a dictionary containing the numerical values found
for each corresponding variable in the instance.
•Each element of an instance of a MIPVariable is replaced by its corresponding numerical value.
Note: While a variable may be declared as binary or integer, its value as returned by the solver is of type
float.
EXAMPLE:
sage: p = MixedIntegerLinearProgram()
sage: x = p.new_variable()
sage: y = p.new_variable(dim=2)
sage: p.set_objective(x[3] + 3*y[2][9] + x[5])
sage: p.add_constraint(x[3] + y[2][9] + 2*x[5], max=2)
sage: p.solve()
6.0
To return the optimal value of y[2][9]:
sage: p.get_values(y[2][9])
2.0
To get a dictionary identical to x containing optimal values for the corresponding variables
sage: x_sol = p.get_values(x)
sage: x_sol.keys()
[3, 5]
18 Chapter 2. Mixed integer linear programming