thnx i got it working.
Am 30.07.2010 12:00, schrieb Harald Schilly:
> On 30 Jul., 00:01, Johannes <dajo.m...@web.de> wrote:
>
>> Hi list,
>> i try to solve a linear equation in ZZ in the variables w_i:
>>
> Here is a MILP formulation of your problem, I've pasted the input cell
> in {{{}}} and the output in between
>
> {{{
> p = MixedIntegerLinearProgram(maximization=False)
> # not reals, we want integers
> w = p.new_variable(integer=True)
> p.add_constraint(w[0] + w[1] + w[2] - 14*w[3] == 0)
> p.add_constraint(w[1] + 2*w[2] - 8*w[3] == 0)
> p.add_constraint(2*w[2] - 3*w[3] == 0)
> # we don't want the trivial solution
> p.add_constraint(w[3] >= 1)
> # minimum of each variable is 0 by default, make it +infinity
> [p.set_min(w[i], None) for i in range(1,4) ]
> # minimize w3
> p.set_objective(w[3])
> # show what we have created so far
> p.show()
> }}}
>
>
> Minimization:
> x_3
> Constraints:
> 0 <= x_0 +x_1 +x_2 -14 x_3 <= 0
> 0 <= x_1 +2 x_2 -8 x_3 <= 0
> 0 <= 2 x_2 -3 x_3 <= 0
> -1 x_3 <= -1
> Variables:
> x_0 is an integer variable (min=0.0, max=+oo)
> x_1 is an integer variable (min=-oo, max=+oo)
> x_2 is an integer variable (min=-oo, max=+oo)
> x_3 is an integer variable (min=-oo, max=+oo)
>
> {{{
> # solve it (default is GLPK, there are other solvers, too)
> print 'Objective Value:', p.solve()
> }}}
>
> Objective Value: 2.0
>
> {{{
> p.get_values(w)
> }}}
>
> {0: 15.0, 1: 10.0, 2: 3.0, 3: 2.0}
>
> {{{
> # to get one value as integer
> w_sol = p.get_values(w)
> int(round(w_sol[2]))
> }}}
>
> 3
>
>
> greetings H
>
>
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