Introduction to MATLAB

1. Introduction to MATLAB CBE 502 Mathematical Methods of Engineering Analysis

2. Where to get MATLAB • Princeton Software : Office of Information Technology (OIT) • http://www.princeton.edu/software/licenses/software/matlab/

3. What is MATLAB • High level language useful for technical computing with extensive library of mathematical and graphical subroutines • Stands for MATrixLABoratory

4. MATLAB Desktop

5. MATLAB Introduction • Creating Matrices • A=[1,2,3;4,5,6;7,8,9]; • Will give a 3 X 3 matrix • A= 1 2 3 4 5 6 7 8 9 • Very easy to access/modify each element A(i,j)

6. MATLAB Introduction • zeros(m, n):matrix with all zeros • ones(m, n): matrix with all ones. • eye(m, n): the identity matrix • rand(m, n): uniformly distributed random • randn(m, n): normally distributed random • magic(m): square matrix whose elements have the same sum, along the row, column and diagonal.

7. MATLAB Introduction • Colon Notation ‘:’ • Generating Vector • Step Size • Access to part of Matrix • ‘end’ Notation

8. MATLAB Introduction • Operators • ^:exponentiation • *: multiplication • /: division • \: left division. The operation A\Bis effectively the same as INV(A)*B, although left division is calculated differently and is much quicker. • +: addition • -: subtraction • Pay attention to size of the arrays

9. Relational/Logical Operator • == Equal to • ~= Not equal to • < Strictly smaller • > Strictly greater • <= Smaller than or equal to • >= Greater than equal to • & And operator • | Or operator

10. MATLAB Introduction • Element by Element .^ , .* , ./ • Different from Matrix Operation • Flow Controls • If, else, for , while , break.. • M File • text file containing program to run

11. Built In Functions • mean(A):mean value of a vector • max(A), min (A): maximum and minimum. • sum(A): summation. • sort(A): sorted vector • median(A): median value • std(A): standard deviation. • det(A) : determinant of a square matrix • dot(a,b): dot product of two vectors • Cross(a,b): cross product of two vectors • Inv(A): Inverse of a matrix A

12. Some Useful/Interesting MATLAB Commands • who List known variables • whos List known variables plus their size • help >> help sqrt Help on using sqrt • lookfor >> lookforsqrt Search keyword sqrt in m-files • what >> what a: List MATLAB files in a: • clear Clear all variables from work space • clear x y Clear variables x and y from work space • clc Clear the command window • any (x) returns 1 if any element of x is nonzero • all (x) returns 1 if all elements of x are nonzero • isnan (x) returns 1 at each NaN in x • isinf (x) returns 1 at each infinity in x • finite (x) returns 1 at each finite value in x

13. 2D Plots • Important Functions • plot , hold , title , xlabel, ylabel , legend • Sub plots , saveas ,

14. Examples • MATLAB.. Here we come !!

15. Keep on exploring MATLAB .. • May the Coding force be with you • Thanks..