Products & Services Solutions Academia Support User Community Company

Learn more about Optimization Toolbox   

Displaying Iterative Output

Introduction

When you set 'Display' to 'iter' or 'iter-detailed' in options, the optimization functions display iterative output in the Command Window. This output, which provides information about the progress of the algorithm, is displayed in columns with descriptive headings. For more information about iterations, see Iterations and Function Counts.

For example, if you run medium-scale fminunc with 'Display' set to 'iter', the output headings are

                                                 First-order 
Iteration    Func-count  f(x)      Step-size     optimality

Most Common Output Headings

The following table lists some common output headings of iterative output.

Output HeadingInformation Displayed

Iteration or Iter

Iteration number; see Iterations and Function Counts

Func-count or F-count

Number of function evaluations; see Iterations and Function Counts

x

Current point for the algorithm

f(x)

Current function value

Step-size

Step size in the current search direction

Norm of step

Norm of the current step

Function-Specific Output Headings

The following sections describe output headings of iterative output whose meaning is specific to the optimization function you are using.

bintprog

The following table describes the output headings specific to bintprog.

bintprog Output HeadingInformation Displayed

Explored nodes

Cumulative number of explored nodes

Obj of LP relaxation

Objective function value of the linear programming (LP) relaxation problem

Obj of best integer point

Objective function value of the best integer point found so far. This is an upper bound for the final objective function value.

Unexplored nodes

Number of nodes that have been set up but not yet explored

Best lower bound on obj

Objective function value of LP relaxation problem that gives the best current lower bound on the final objective function value

Relative gap between bounds

where

  • b is the objective function value of the best integer point.

  • a is the best lower bound on the objective function value.

fminsearch

The following table describes the output headings specific to fminsearch.

fminsearch Output HeadingInformation Displayed

min f(x)

Minimum function value in the current simplex

Procedure

Simplex procedure at the current iteration. Procedures include initial, expand, reflect, shrink, contract inside, and contract outside. See fminsearch Algorithm for explanations of these procedures.

fzero and fminbnd

The following table describes the output headings specific to fzero and fminbnd.

fzero and fminbnd Output HeadingInformation Displayed

Procedure

Procedure at the current operation. Procedures for fzero:

  • initial (initial point)

  • search (search for an interval containing a zero)

  • bisection (bisection search)

  • interpolation

Operations for fminbnd:

  • initial

  • golden (golden section search)

  • parabolic (parabolic interpolation)

fminunc

The following table describes the output headings specific to fminunc.

fminunc Output HeadingInformation Displayed

First-order optimality

First-order optimality measure (see First-Order Optimality Measure)

CG-iterations

Number of conjugate gradient iterations taken by the current (optimization) iteration (see Preconditioned Conjugate Gradient Method)

fsolve

The following table describes the output headings specific to fsolve.

fsolve Output HeadingInformation Displayed

First-order optimality

First-order optimality measure (see First-Order Optimality Measure)

Trust-region radius

Current trust-region radius (change in the norm of the trust-region radius)

Residual

Residual (sum of squares) of the function

Directional derivative

Gradient of the function along the search direction

fgoalattain, fmincon, fminimax, and fseminf

The following table describes the output headings specific to fgoalattain, fmincon, fminimax, and fseminf.

fgoalattain, fmincon, fminimax, fseminf Output HeadingInformation Displayed

Max constraint

Maximum violation among all constraints, both internally constructed and user-provided

First-order optimality

First-order optimality measure (see First-Order Optimality Measure)

CG-iterations

Number of conjugate gradient iterations taken by the current (optimization) iteration (see Preconditioned Conjugate Gradient Method)

Trust-region radius

Current trust-region radius

Residual

Residual (sum of squares) of the function

Attainment factor

Value of the attainment factor for fgoalattain

Objective value

Objective function value of the nonlinear programming reformulation of the minimax problem for fminimax

Directional derivative

Current gradient of the function along the search direction

Procedure

Hessian update and QP subproblem. The Procedure messages are discussed in Updating the Hessian Matrix.

linprog

The following table describes the output headings specific to linprog.

linprog Output HeadingInformation Displayed

Primal Infeas A*x-b

Primal infeasibility

Dual Infeas A'*y+z-w-f

Dual infeasibility

Duality Gap x'*z+s'*w

Duality gap (see Large Scale Linear Programming) between the primal objective and the dual objective. s and w appear only in this equation if there are finite upper bounds.

Total Rel Error

Total relative error, described at the end of Main Algorithm.

Objective f'*x

Current objective value

lsqnonlin and lsqcurvefit

The following table describes the output headings specific to lsqnonlin and lsqcurvefit.

lsqnonlin and lsqcurvefit Output HeadingInformation Displayed

Resnorm

Value of the squared 2-norm of the residual at x

Residual

Residual vector of the function

First-order optimality

First-order optimality measure (see First-Order Optimality Measure)

CG-iterations

Number of conjugate gradient iterations taken by the current (optimization) iteration (see Preconditioned Conjugate Gradient Method)

Directional derivative

Gradient of the function along the search direction

Lambda

λk value defined in Levenberg-Marquardt Method. (This value is displayed when you use the Levenberg-Marquardt method and omitted when you use the Gauss-Newton method.)

  


Recommended Products

Includes the most popular MATLAB recorded presentations with Q&A sessions led by MATLAB experts.

 © 1984-2009- The MathWorks, Inc.    -   Site Help   -   Patents   -   Trademarks   -   Privacy Policy   -   Preventing Piracy   -   RSS