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Science Forum Index » Math - Numerical Analysis Forum » Large-scale coupled optimization problems...
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| Paul Smith... |
Posted: Mon May 05, 2008 7:36 am |
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Dear All,
Define
f1(x) = x * (1 - x - y)
and
f2(y) = y * (1 - x - y).
Consider now the following coupled optimization problem:
max f1(x) and max f2(y) (simultaneously).
I know that the analytical solution is
x = 1/3 and y = 1/3,
but how can one solve this numerically? My question is motivated by
the fact that I have to solve similar problems, but large-scale ones.
Thanks in advance,
Paul |
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| Hans Mittelmann... |
Posted: Mon May 05, 2008 9:08 am |
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On May 5, 10:36 am, Paul Smith <phh... at (no spam) gmail.com> wrote:
Quote: Dear All,
Define
f1(x) = x * (1 - x - y)
and
f2(y) = y * (1 - x - y).
Consider now the following coupled optimization problem:
max f1(x) and max f2(y) (simultaneously).
I know that the analytical solution is
x = 1/3 and y = 1/3,
but how can one solve this numerically? My question is motivated by
the fact that I have to solve similar problems, but large-scale ones.
Thanks in advance,
Paul
max t
s.t. t <= f1(x)
t <= f2(x) |
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| Paul Smith... |
Posted: Mon May 05, 2008 10:37 am |
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On May 5, 8:08 pm, Hans Mittelmann <mittelm... at (no spam) asu.edu> wrote:
Quote: Define
f1(x) = x * (1 - x - y)
and
f2(y) = y * (1 - x - y).
Consider now the following coupled optimization problem:
max f1(x) and max f2(y) (simultaneously).
I know that the analytical solution is
x = 1/3 and y = 1/3,
but how can one solve this numerically? My question is motivated by
the fact that I have to solve similar problems, but large-scale ones.
max t
s.t. t <= f1(x)
t <= f2(x)
Thanks, Hans. Do you mean to run your optimization program on the 3
variables, x, y and t? If so, it does not lead to the correct
solution; by optimizing numerically, I get the following solution:
x = 0.25
y = 0.25
Paul |
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| ... |
Posted: Mon May 05, 2008 10:38 am |
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Guest
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On May 5, 10:36 am, Paul Smith <phh... at (no spam) gmail.com> wrote:
Quote: Dear All,
Define
f1(x) = x * (1 - x - y)
and
f2(y) = y * (1 - x - y).
Consider now the following coupled optimization problem:
max f1(x) and max f2(y) (simultaneously).
Both f1 and f2 depend on both x and y. Do you mean that you only want
to maximize f1 wrt x and f2 wrt y, i.e. find (x,y) such that
x (1 - x - y) >= x' (1 - x' - y) for all x' and
y (1 - x - y) >= y' (1 - x - y') for all y'?
Or do you want to somehow maximize both objectives with respect to
both variables?
Quote: I know that the analytical solution is
x = 1/3 and y = 1/3,
I guess this supports the first interpretation...
Quote: but how can one solve this numerically? My question is motivated by
the fact that I have to solve similar problems, but large-scale ones.
You could use numerical methods to look for solutions to the equations
df1/dx = 0, df2/dy = 0.
Robert Israel israel at (no spam) math.MyUniversitysInitials.ca
Department of Mathematics http://www.math.ubc.ca/~israel
University of British Columbia Vancouver, BC, Canada |
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| Paul Smith... |
Posted: Mon May 05, 2008 10:49 am |
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On May 5, 9:38 pm, isr... at (no spam) math.ubc.ca wrote:
Quote: f1(x) = x * (1 - x - y)
and
f2(y) = y * (1 - x - y).
Consider now the following coupled optimization problem:
max f1(x) and max f2(y) (simultaneously).
Both f1 and f2 depend on both x and y. Do you mean that you only want
to maximize f1 wrt x and f2 wrt y, i.e. find (x,y) such that
x (1 - x - y) >= x' (1 - x' - y) for all x' and
y (1 - x - y) >= y' (1 - x - y') for all y'?
Or do you want to somehow maximize both objectives with respect to
both variables?
I know that the analytical solution is
x = 1/3 and y = 1/3,
I guess this supports the first interpretation...
but how can one solve this numerically? My question is motivated by
the fact that I have to solve similar problems, but large-scale ones.
You could use numerical methods to look for solutions to the equations
df1/dx = 0, df2/dy = 0.
Yes, Robert, your first interpretation corresponds to what I wanted to
mean.
I had already had the idea of solving numerically
df1/dx = 0, df2/dy = 0,
but, in my large-scale problem, it can be messy. Therefore it would be
of great help if one could convert the problem into another one
solvable by the available large-scale optimization numeric algorithms.
Paul |
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