# a nonlinear problem

• July 23rd 2010, 10:26 AM
zhu1984
a nonlinear problem
I am not sure that I post at the right palce, because I don't know which topic my problem should belong to. So sorry for that.

Given some variables a1, a2, a3... an, and some constraints based on these variables, like:
a1 + a2 >0,
a3 - a5 >0,
a4 - a3 + a2 <0,
....
How to get a solution for variables, that maximun the positive number of variables. That means, make as much of
the variables positive. I even don't know which area this topic should belong to. Please help. Thanks in advance!
steve
• July 24th 2010, 08:40 AM
Mush
In general, if you have a non-linear problem in which you have to maximise or minimise something whilst paying due consideration to constrain equations, it's a problem of non-linear programming.

$\displaystyle \max_{c} (a_1, a_2, a_3, ..., a_n)$ where $c$ represents your constraint equations.
• July 24th 2010, 12:04 PM
zhu1984
But is there any practical way to solve it?
• July 24th 2010, 12:46 PM
Ackbeet
Try gnumeric.
• July 24th 2010, 04:51 PM
Mush
Quote:

Originally Posted by zhu1984
I am not sure that I post at the right palce, because I don't know which topic my problem should belong to. So sorry for that.

Given some variables a1, a2, a3... an, and some constraints based on these variables, like:
a1 + a2 >0,
a3 - a5 >0,
a4 - a3 + a2 <0,
....
How to get a solution for variables, that maximun the positive number of variables. That means, make as much of
the variables positive. I even don't know which area this topic should belong to. Please help. Thanks in advance!
steve

I'd like to guide you to a practical solution to this problem, but I'm not sure if you've given us the full problem, have you?

In your question, you said you had n variables, and gave us three constraint equation which involved only 5 of those n variables. How many variables are there, and are there any more constraint equations?
• July 24th 2010, 05:20 PM
zhu1984
The number of variables can be 200 or more. And all of the variables are involved in constraints. The example I gave may not clear enough.