1 MatLab Basics Jae Hoon Kim Department of Physics Kangwon National University It contains hundreds of commands to do mathematics. Graph functions, solve equations, perform statistical tests High level programming language that can communicate with the other programming language such as FORTRAN and C.

2 MatLab Desktop Workspace Display the information for the defined variables Command window Enter the command and Output the result Command History List of used commands  Double click the MatLab icon on the Windows Desktop → Launch the MatLab → MatLab Desktop appears:

3 Arithmetic Simple Arithmetic (1) Four fundamental operations : +, -, *, / >> 3^2-(5+4)/2+6*3 ans= (2) Mathematic Functions: sqrt, cos, sin, tan >> ans^2+sqrt(ans) ans= Precision (1) MATLAB uses double-precision floating point arithmetic. -> 15 digits (2) MATLAB display only 5 digits for the output result by default. Format long -> display 15 digits Format short -> return to 5-digit display

4 Algebraic and Symbolic Calculation To perform symbolic calculation, use “syms” command to declare the symbolic variable. >> syms x y >> (x-y)*(x-y)^2 ans = (x-y)^3 Commands for the symbolic calculation (1) expand: multiply out the expression >> expand(ans) ans = x^3-3*x^2*y+3*x*y-y^3 (2) factor: restore to factored form >> factor(ans) ans = (x-y)^3 (3) simplify: express a formula as simply as possible. >> simplify((x^3-y^3)/(x-y)) ans = x^2+x*y+y^2 Calculation with the Symbolic Expression >> cos(pi/2) -> e-17 (not 0) Because “pi” gives an approximation to  accurate to about 15 digits, not its exact value. >> cos(sym(‘pi/2’)) ->0 Symbolic representation of  /2 -> exact value. Variable – precision Arithmetic >> vpa(‘sqrt(2)’, 50) print 50 digits of √ 2

5 Managing Variables Data type (1) floating point numbers (2) symbolic expressions (3) strings “ whos ” command: display a summary of the names and types of currently, defined variables. (Workspace browser presents a graphical alternative to “ whos ”) “ clear ” or “ clear all ” : Clear all defined variables

6 Online Help  To get help on a command, enter help followed by the name of the command. ex) help solve: print out the online help for “solve” command. more on: Display the online help. One screen-full at a time  To search the first line of every online help for a specified string use “ lookfor ” command ex) lookfor factor : Display the help that contain the word “ factor ” as part of the command name of brief description