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An Introduction to Optimization Theory. Outline Introduction Unconstrained optimization problem Constrained optimization problem.

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Presentation on theme: "An Introduction to Optimization Theory. Outline Introduction Unconstrained optimization problem Constrained optimization problem."— Presentation transcript:

1 An Introduction to Optimization Theory

2 Outline Introduction Unconstrained optimization problem Constrained optimization problem

3 Introduction Mathematically speaking, optimization is the minimization of a objective function subject to constraints on its variables. Mathematically, we have

4 Introduction

5 Introduction-Linear regression

6 Introduction-Battery charger

7 Unconstrained optimization problem Definition for unconstrained optimization problem:

8 Unconstrained optimization problem

9 Gradient descent algorithm

10 Gradient descent algorithm may be trapped into the local extreme instead of the global extreme

11 Gradient descent algorithm Methodology for choosing suitable step size α k ---- Steepest descent algorithm

12 Gradient descent algorithm

13 Steepest descent algorithm with quadratic cost function:

14 Gradient descent algorithm Update equation:

15 Newton method Summary for Newton method

16 Newton method

17 Procedure for Newton method

18 Quasi-Newton method

19 What properties of F(x (k) ) -1 should it mimic ? 1. H k should be a symmetric matrix 2. H k should with secant property

20 Quasi-Newton method Typical approaches for Quasi-Newton method 1. Rank-one formula 2. DFP algorithm 3. BFGS algorithm (L-BFGS, L indicates limited-memory)

21 Constrained optimization problem Definition for constrained optimization problem

22 Problems with equality constraints ---- Lagrange multiplier

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25 Suppose x * is a local minimizer

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27 Karush-Kuhn-Tucker condition (KKT) From now on, we will consider the following problem

28 Karush-Kuhn-Tucker condition (KKT) Note that:

29 Image statistics & Image enhancement Illustration for gradient descent with projection Constrained set Ω Initial solution Projection

30 Useful Matlab introductions for optimization Useful instructions included in Matlab for optimization 1. fminunc: Solver for unconstrained optimization problems 2. fmincon: Solver for constrained optimization problems 3. linprog: Solver for linear programming problems 4. quadprog: Solver for quadratic programming problems


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