A class for solving linear programs.
Bases: NumberTypeable
Parameters: | mat (Matrix) – The matrix to load the linear program from. |
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Solve linear program.
Parameters: | solver (int) – The method of solution (see LPSolverType). |
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A tuple containing the dual solution.
The optimal value of the objective function.
A tuple containing the primal solution.
The type of solver to use (see LPSolverType).
The status of the linear program (see LPStatusType).
Note that the following examples presume:
>>> import cdd
This is the testlp2.c example that comes with cddlib.
>>> mat = cdd.Matrix([['4/3',-2,-1],['2/3',0,-1],[0,1,0],[0,0,1]], number_type='fraction')
>>> mat.obj_type = cdd.LPObjType.MAX
>>> mat.obj_func = (0,3,4)
>>> print(mat)
begin
4 3 rational
4/3 -2 -1
2/3 0 -1
0 1 0
0 0 1
end
maximize
0 3 4
>>> print(mat.obj_func)
(0, 3, 4)
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> lp.status == cdd.LPStatusType.OPTIMAL
True
>>> print(lp.obj_value)
11/3
>>> print(" ".join("{0}".format(val) for val in lp.primal_solution))
1/3 2/3
>>> print(" ".join("{0}".format(val) for val in lp.dual_solution))
3/2 5/2
Another example.
>>> mat = cdd.Matrix([[1,-1,-1,-1],[-1,1,1,1],[0,1,0,0],[0,0,1,0],[0,0,0,1]], number_type='fraction')
>>> mat.obj_type = cdd.LPObjType.MIN
>>> mat.obj_func = (0,1,2,3)
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> print(lp.obj_value)
1
>>> mat.obj_func = (0,-1,-2,-3)
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> print(lp.obj_value)
-3
>>> mat.obj_func = (0,'1.12','1.2','1.3')
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> print(lp.obj_value) # 28/25 is 1.12
28/25
>>> print(lp.primal_solution) # extreme point in simplex
(1, 0, 0)
This is the testlp2.c example that comes with cddlib.
>>> mat = cdd.Matrix([['4/3',-2,-1],['2/3',0,-1],[0,1,0],[0,0,1]])
>>> mat.obj_type = cdd.LPObjType.MAX
>>> mat.obj_func = (0,3,4)
>>> print(mat)
begin
4 3 real
1.333333333E+000 -2 -1
6.666666667E-001 0 -1
0 1 0
0 0 1
end
maximize
0 3 4
>>> print(mat.obj_func)
(0.0, 3.0, 4.0)
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> lp.status == cdd.LPStatusType.OPTIMAL
True
>>> print(lp.obj_value)
3.66666...
>>> print(" ".join("{0}".format(val) for val in lp.primal_solution))
0.33333... 0.66666...
>>> print(" ".join("{0}".format(val) for val in lp.dual_solution))
1.5 2.5
Another example.
>>> mat = cdd.Matrix([[1,-1,-1,-1],[-1,1,1,1],[0,1,0,0],[0,0,1,0],[0,0,0,1]])
>>> mat.obj_type = cdd.LPObjType.MIN
>>> mat.obj_func = (0,1,2,3)
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> print(lp.obj_value)
1.0
>>> mat.obj_func = (0,-1,-2,-3)
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> print(lp.obj_value)
-3.0
>>> mat.obj_func = (0,'1.12','1.2','1.3')
>>> lp = cdd.LinProg(mat)
>>> lp.solve()
>>> print(lp.obj_value) # 28/25 is 1.12
1.12