Intro to Matlab Rogelio Long September 3, 2013

How to access MyDesktop Log in with your utep id and password Proceed/Install Citrix(wait for the DL)/Continue

Why use Matlab? Pros Easy to learn Many built in functions that you may otherwise have to find libraries for Easy to program Cons Not free

An expensive calculator Basic numerical operations: +,-,*,/,^ Don’t have to declare a data type Inf Nan Complex ex i

Some useful functions Sin, cos, tan, acos, asin, atan Sqrt, exp,log,log10 Floor, ceil, sign, rem,mod Sum, max, min find

Vectors a =[2 12 5] row vector b =[3+ 2 5] c =[A 2*B] d= [5;3;7] column vector e = 1:4 f=2:2:8

Matrices A = [2,4;5,1] B = [1:4;5:8] C = zeros(3,3) (all zeros) D = ones(4,2) (all ones) E = rand(2,2) (random number between 0-1) F = eye(3) (identity matrix)

Extracting a value from a Matrix/Vector a(2)=? c(1:2:5)=? A(1,2) = ? (outputs the value in row 1 column 2) A(3) = ? (outputs the value at index 3 column major) A(2,:) = ? (outputs row 2) A(:,2) = ? (outputs column 2)

Logicals true =1 False =0 ==,~=,>, =,<= And & Or |

Matrix operations A’ (Transpose ) A^-1, inv(A) (Inverse ) eig(A) (Eigen value ) norm(A) (Norm of a matrix ) diag(A) (extracts the diagonal of a matrix) diag(a) (turns a array into a diagonal matrix) diag(diag(A))(turns the diagonal of a matrix into a diagonal matrix)

Size of a matrix/array Size(A) (outputs [num row, num columns]) Length(a) (outputs length of an array)

Neat matrix building A = [1:3;4:6;7:9] B = [diag(diag(A)) A;A' rand(3,3)] B(4,4)=12 B(8,9)=3 (set a value out of bounds for matrix B) C = [B b] (adds array b to matrix B)

Matrix/vector arithmetic A+B A-B A*B (assuming A & B could bemultiplied) A/B (this is like A*inv(B)) A.*B A./B A^x A.^x Ax = b  x = inv(A)*b or A\b

Formats format short “ “long “ “ short e “ “ long e

Creating a script/function File/new/script F5 save&run File/new/function function [ output_args ] = foo( input_args ) foo(x) (how to call a function)

loops for i=1:2:11 …. end while test is true …. End if true …. else …. end Break (ends the deepest loop you are in)

Printing output disp(X) disp(‘some words’) fprintf(‘some words %5.3d \n’, X)

Plots x = linspace(0,2*pi, 100) y = sin(x) plot(x,y) title(‘something”) xlabel(‘x’) ylabel(‘y’)

Plots color -y,m,c,r,g,b,w,b line styles -,o,x,+,-,*,:,-.,-- plot(…….,‘LineWidth’,number…….,’) grid hold on hold off

Viewing a matrix Imagesc(B); colorbar Axis equal tight xa = linspace(-1,1,100); ya = linspace(-1,1,100); [X,Y] = meshgrid(xa,ya); A = (X.^2 + Y.^2)<=0.75

3D plots [X,Y] = meshgrid(-2:.1:2,-2:.1:2); Z = sqrt(X.^2 + Y.^2) Z = -X.*Y.*exp(-2*(X.^2+Y.^2)); Mesh(X,Y,Z) Contour(X,Y,Z)

Other stuff diary on diary off diary name (sets a name to the diary file) Help feature demo

Exercise fibonacci Create script that calls a function