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Linear programming is the study of optimizing a linear function over a set of linear inequalities. The Simplex Method, Ellipsoid Method and Interior Point Method are popular algorithms to solve linear programs.

1 vote

SDP Algorithms/ maximally complementary solutions

The standard approach is to embed the original SDP in a self dual formulation that has strictly feasible primal/dual solutions, solve the self dual formulation and then reach conclusions about the ori …
Brian Borchers's user avatar
3 votes
Accepted

Cascading minimization problems

You can solve the first LP, obtain the optimal value, and then add a constraint that the first objective has that optimal value. Then you can add your second set of constraints to the original set of …
Brian Borchers's user avatar
2 votes

Levenberg-Marquadt near the minima for non-zero-residual problems

The technique of multiplying the diagonal by $(1+\lambda)$ fails when you've got a 0 on the diagonal of $J^{T}J$. Having a zero on the diagonal of $J^{T}J$ can happen when you're far away from the op …
Brian Borchers's user avatar
1 vote
Accepted

Nonstandard Hessian approximations in Gauss-Newton

You could certainly try this, but you'd have to do a lot of careful analysis to derive any convergence results. Among other things to consider: Your objective E(x) is more likely to have local mini …
Brian Borchers's user avatar
1 vote
Accepted

What does "Vertex Solution" mean?

In the context of linear programming, and assuming that you're using the simplex method to solve your LP's rather than an interior point method, it's most likely that the author means "basic feasible …
Brian Borchers's user avatar
2 votes
Accepted

Model for shipping widgets in an optimal way

Is the routing from factory to distributor to location fixed, or are you considering optimizing this too? In particular, are there costs associated with using a distributor? If the answers to one or …
Brian Borchers's user avatar
3 votes
Accepted

linear programming with OR restrictions

Your additional constraints make the feasible region for your problem nonconvex, and thus it cannot be represented as a linear programming problem. If you can obtain an upper bound $M_{i}$ on the max …
Brian Borchers's user avatar
1 vote
Accepted

Large scale least squares of non symmetric and non square problems

A widely used iterative method for large scale linear least squares problems that allows for regularization if you want/need it is the LSQR algorithm of Paige and Saunders. See http://www.stanford.ed …
Brian Borchers's user avatar
1 vote

positive semidefiniteness: a psd matrix substracted by another rank 1 psd matrix

This is easy to formulate as a semidefinite programming problem. First, let $X=xx^{T}$. The semidefiniteness constraint becomes $A-\lambda X \succeq 0$ Next, use a standard technique to handle t …
Brian Borchers's user avatar
1 vote

generalization from linear programming solution

You should look into the topic of "parameteric linear programming". In certain situations where the problem data vary linearly with parameters, you can derive formulas for the optimal solution and op …
Brian Borchers's user avatar
1 vote

Efficient Algorithm For Projection Onto A Convex Set

You haven't told us anything about the size of your problem instances. How many terms are there in the sum of norms? What is $n$? Your problem is an example of a "sum of norms" optimization probl …
Brian Borchers's user avatar
1 vote

Continuity of Lexicographic Minimum Solution of a parametrized LP problem

You've chosen a somewhat limited form of "parametric LP" here. It's more common to allow $F$ to vary as $F=F_{0}+tF_{1}$. For that more general variety of parametric LP, the conjecture is false- it' …
Brian Borchers's user avatar
0 votes

Existence of nonnegative solutions to an underdetermined system of linear equations

Algorithmically, you can solve the linear programming problem: $\max \sum_{i=1}^{n} x_{i} $ $Ax=0$ $x \geq 0$ If the maximum is strictly greater than zero, then there's a nonzero solution that sa …
Brian Borchers's user avatar
9 votes

How do you tell if a system of linear inequalities has a solution?

You haven't said whether you're interested in theoretical analysis or practical computation. At the practical level, you also haven't specified whether you can live with an approximate floating poin …
Brian Borchers's user avatar
2 votes

Sensitivity analysis in conic optimization

In general, your problem can become infeasible under arbitrarily small perturbations $\Delta b$. For example, consider the problem $\min X_{11}+X_{22}$ subject to $X_{11}=0$ $X_{22}=0$ $X \suc …
Brian Borchers's user avatar

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