Department of Mathematics

Math 300: Mathematical Computing

Matlab Cheat Sheet

Defining Matrices

Row vector x=[1 2 3]
Column vector x=[1 2 3]'

A = [1 2; 3 4]


A=[1 2

3 4]

Transpose - use the apostrophe B = A'
Addition C=A+B
Multiplication D = A*B


By integers from 0 to N x=0:N
By steps of .1 x=0:.1:N
Assign part of a matrix E(3:4,1:2) = A
Assign an entire column of a matrix F(:,1) = x'


Size of a matrix [m,n] = size(A)
Length of a vector n = length(x)

Special Functions

Trig functions




Zero matrix

N x N zero matrix

M x N zero matrix




Identity matrix eye(N)

Random matrix

N x N random matrix with entries between 0 and 1

M x N random matrix





2-D plot with abscissae in x, ordinates in y plot(x,y)
2-D plot of sin(x) plot(x,sin(x))
2-D plot of sin(x) using green diamonds to indicate points plot(x,sin(x),'gd')

Saving and Loading

Save current variables in "matlab.mat" save
Save current variables in "myfile.mat" save myfile
Load variables from "matlab.mat" load
Load variables from "myfile.mat" load myfile
Read comma-delimited data from "myfile.csv" dlmread('myfile.csv',',')
Read space-delimited data dlmread('myfile.csv',' ')


Eigenvalues of a matrix eig(A)
Eigenvalues and eigenvectors of A [evec,eval]=eig(A)
QR decomposition of a matrix [Q,R] = qr(A)

Gauss elimination

LU decomposition of a matrix [L,U] = lu(A)
LU with a permutation matrix [L,U,P] = lu(A)
Cholesky decomposition of a symmetric matrix R = chol(A)
Solve Ax = b for x x = A\b


The "final exam" for this course will take place at 8:00 AM on Tuesday, 12 December. This will be an ordinary 50 minute test. It will be comprehensive, but weighted toward the latter half of the semester. As always, paper notes will be permitted, but no electronic devices will be allowed.

A Solution example is available for the quiz.

Assignment A is posted.

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