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visits member for 2 years, 11 months
seen May 31 '13 at 8:02

May
30
awarded  Supporter
May
30
comment Is the following optimization problem convex?
Thank you very much for the answer! Regarding your latest sentence (about linear assignment problems) I'll try to investigate. Perhaps, do you have any hint or known any source (books, URLs, ...) to look for it?
May
30
accepted Is the following optimization problem convex?
May
29
awarded  Editor
May
29
revised Is the following optimization problem convex?
deleted 5 characters in body
May
29
asked Is the following optimization problem convex?
Aug
1
comment Convert a linear difference equation into a controllable state-space model
Hi, I have some questions? * Does this system is a realization of the original input-output model (i.e., they realize the same transfer function)? * Is this system in controllable form? Thanks
Feb
19
awarded  Tumbleweed
Feb
12
asked Convert a linear difference equation into a controllable state-space model
Sep
3
comment How to solve mixed integer nonlinear programs?
@thomas: thank you for the hints! I will try to rearrange the problem in order to avoid the product of two decision variables.
Sep
2
comment How to solve mixed integer nonlinear programs?
@thomas: I did not assume my problem is easy to solve (sorry for this misunderstanding). I read MINLP is a hard topic. I would like to know the way to solve this problem. I also read of many solution techniques, but honestly I don't know what to choose. For what concerns my math knowledge, I am a PhD Student in Computer Science, so I (should) know intermediate math. Indeed, I know what convex functions are and how to solve a linear program with the simplex method. For what regards constrained optimization principles...I give up. Now, I'm trying to compute the Hessian but with some trouble.
Sep
1
asked How to solve mixed integer nonlinear programs?
Aug
18
comment Range scaling with constraints
@André: You're right, another good catch! Unfortunately I cannot say too much about $x_i$ and $n$ in advance.I've just noted that the solution given by Shai fails too :( At this point, I think the best can do is removing the constraint $x_i>a$. Thanks
Aug
18
awarded  Scholar
Aug
18
comment Range scaling with constraints
Beautiful answer! It works like a charm.Thank you very much!
Aug
18
comment Range scaling with constraints
@André: good catch. Indeed, this could be a problem. However, I think that a simple normalization should solve it. That is: $x_i \rightarrow \frac{x_i}{\sum_{i}x_i} \rightarrow \hat{x}_i$. Do you?
Aug
18
comment Range scaling with constraints
@JM: can you be more explicit, that is $\hat{x}_i=\ldots$?
Aug
18
comment Range scaling with constraints
It does not work since in this case $\hat{x}_1 \notin [0.2,0.8]$.
Aug
18
awarded  Student
Aug
18
asked Range scaling with constraints