Your objective: to dominate! My objective: to help you dominate! Matlab® refresher Your objective: to dominate! My objective: to help you dominate!

Some references MATLAB Student Version: Learning MATLAB, The MathWorks, Inc. Introduction to MATLAB 6 for Engineers, W.J.Palm III, McGraw-Hill. Numerical Methods with MATLAB, G.Recktenwald, Prentice Hall.

Key concept: the Workspace (WS) The Workspace (WS) contains all of your currently active variables and relations. These are initially entered by typing commands (most likely). Useful Workspace commands: Clear : empty the WS Who (whos) : show what is in the WS Save <filename>: save all WS variables to file Load <filename>: retrieve a particular WS from file

Key concept: WS inputs WORKSPACE Command line inputs Script file inputs Workspace file inputs

Key concept: WS outputs Diary files WORKSPACE Workspace files Graphics (plot) files

Script files Script files are text files that are created using the MATLAB script file editor. They usually have the suffix .m. A script file can be run from the command line or toolbar. Two items to remember about .m files: Use “%” to enter comments for your use. Use “;” at the end of lines to suppress echo printing when the file is run.

More about the Workspace Recording your MATLAB session can be useful for documentation. Useful Workspace commands: Diary <filename> : turn on recording of all text i/o except plots, save into <filename> Diary off : turn off current recording Path : pointer to current directory Pathtool : directory browser

A typical session pattern Clear Diary Problem1 { create data etc here …} Pa= 14.7; R= 245.6; P= 23; Q = (1/R)*(P-Pa); who Save Problem1Run1 Diary off You now have 2 files: Problem1: a diary of this session Problem1Run1: a WS file that can be used to recover your last state by using a Load command

Solving Linear Algebraic Equations Define a set of linear algebraic equations as follows: A*X = B*U X is the unknown vector (n x 1) U is the input vector (m x 1) A is n x n, B is n x m In the WS define A, B, and U. Then type X= inv(A)*B*U Click here to see an example session: LAExample1

Solving Linear Algebraic Equations Dominators know that a unique solution to a problem in linear algebra doesn’t always exist. To investigate before you leap try this: Use the command det(A) to check the determinant of A. Proceed accordingly. Sometimes we seek insight in the form of eigenvalues of A. Try this: Type Evals= eig(A). Click here to see an example session: LAExample2

Solving Linear Differential State Equations Define a set of linear algebraic equations: Xdot = A*X + B*U Xdot is the first derivative of X. Create a script (.m) file that defines the equations for MATLAB in a specific format. for example: LDEEqns1.m Create a script file that controls the solving of the problem. click to see an example: LDEExample.pdf