On Mon, May 3, 2010 at 1:21 PM, David Joyner <wdjoy...@gmail.com> wrote:
> On Mon, May 3, 2010 at 12:50 PM, Diego Ruano <dru...@gmail.com> wrote:
>> Thank you David for your answer.
>>
>> What about getting a solution over the integers?
>
>
> I'm sure of the best way. You could just write your own
To correct myself, I meant to say "I'm *not* sure of the best way."
> little function that checks the conditions for each
> (i,j) in a big rectangle. Also, you might be able to use Sage's
> MixedIntegerLinearProgram functionality.
>
> Hopefully others on this list will have a better idea.
>
>
>>
>> David Joyner wrote:
>>> I think Sage calls Maxima and Maxima is getting i (your variable)
>>> and I (sqrt(-1)) mixed up. I guess this is a bug, but it might be
>>> known already.
>>>
>>> Anyway, using x's and y's might be safer:
>>>
>>> sage: x,y = var('x,y')
>>> sage: ineqs = [2*x+9*y>= - 0, -5*x-7*y>=-5, 3*x-2*y>= -6]
>>> sage: solve_ineq(ineqs,[x,y])
>>> [[x == (-32/31), y == (45/31)], [x == (-54/31), y == (12/31)], [x ==
>>> 2/3*y - 2, (12/31) < y, y < (45/31)], [x == (45/31), y == (-10/31)],
>>> [x == -7/5*y + 1, (-10/31) < y, y < (45/31)], [x == -9/2*y, (-10/31) <
>>> y, y < (12/31)], [max(2/3*y - 2, -9/2*y) < x, x < -7/5*y + 1, (-10/31)
>>> < y, y < (45/31)]]
>>>
>>>
>>>
>>>
>>>
>>> On Mon, May 3, 2010 at 5:04 AM, Diego Ruano <dru...@gmail.com> wrote:
>>> > Hi,
>>> >
>>> > I would like to compute the solution of systems of inequalities over
>>> > the integers. I have used the command "solve", but the solution is
>>> > over the complex numbers.
>>> >
>>> > Something like:
>>> >
>>> > i, j = var('i,j')
>>> > sol=solve([2*i+9*j>= - 0, -5*i-7*j>=-5, 3*i-2*j>= -6], i,j)
>>> > sol
>>> > [[i == (-54/31), j == (12/31)], [i == (-32/31), j == (45/31)], [i ==
>>> > (45/31), j == (-10/31)], [i == -7/5*j + 1, (-10/31) < j, j <
>>> > (45/31)], [i == -9/2*j, (-10/31) < j, j < (12/31)], [i == 2/3*j -
>>> > 2, (12/31) < j, j < (45/31)], [max(2/3*j - 2, -9/2*j) < i, i
>>> > < -7/5*j + 1, (-10/31) < j, j < (45/31)]]
>>> >
>>> > Is there any way to get the intersection of the previous set with
>>> > ZZ^2?, or a command to solve the system over the integers?
>>> >
>>> > Thanks,
>>> >
>>> > Diego
>>> >
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>>>
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>>
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