Hey, you know how to install and run MatLab right? Let's skip this part. If you do not know, you can google it. It is too easy.
I use the MatLab 7 Getting Started Guide, which is free (really and legally) from the mathworks website.
Check out the
Chapter 1. Product Overview
Do I look like a salesman? Let's skip this part.
Chapter 2. Matrices and Arrays
Enter matrices into MATLAB in several different ways
Enter maxtrix as a list of elements:
A = [16 3 2 13; 5 10 11 8; 9 6 7 12; 4 15 14 1]
Use a semicolon, ; , to indicate the end of each row. It is automatically remembered in the MATLAB workspace
sum, transpose, and diag
sum(A) => sum of all columns
A' => transpose
diag(A) => main diagonal
fliplr(A) => flips a matrix from left to right
The element in row i and column j of A is denoted by A(i,j).
A(1,4) + A(2,4) + A(3,4) + A(4,4)
It is also possible to refer to the elements of a matrix with a single subscript, A(k). A(8) is another way of referring to the value 15 stored in A(4,2). Conversely, if you store a value in an element outside of the matrix, the size increases to accommodate the newcomer:
The Colon Operator
1:10 => row vector containing the integers from 1 to 10:
1 2 3 4 5 6 7 8 9 10
100:-7:50 => nonunit spacing
100 93 86 79 72 65 58 51
0 0.7854 1.5708 2.3562 3.1416
A(1:k,j) => first k elements of the jth column of A. Thus:
The colon by itself refers to all the elements in a row or column of a matrix and the keyword end refers to the last row or column.
sum(A(:,end)) => computes the sum of the elements in the last column of A
The magic Function
creates magic squares of almost any size: magic(4)
These expressions involve entire matrices.
num_students = 25 => creates a 1-by-1 matrix
Variable names consist of a letter, followed by any number of letters, digits, or underscores. MATLAB is case sensitive; it distinguishes between uppercase and lowercase letters. MATLAB uses only the first N characters of the name, (where N is the number returned by the function namelengthmax), and ignores the rest.
Imaginary numbers (complex number whose squared value is a real number not greater than zero, i think here only means complex number) use either i or j as a suffix.
\ Left division (described in “Linear Algebra” in the MATLAB documentation)
' Complex conjugate transpose
( ) Specify evaluation order
e.g. abs, sqrt, exp, and sin.
help elfun => elementaty maths functions
help specfun => advanced maths functions
help elmat => matrix functions
i Imaginary unit,
j Same as i
eps Floating-point relative precision,
realmin Smallest floating-point number,
realmax Largest floating-point number,
zeros All zeros
ones All ones
rand Uniformly distributed random elements
randn Normally distributed random elements
The load Function - Load content from file
The load function reads binary files containing matrices generated by earlier MATLAB sessions, or reads text files containing numeric data. The text file should be organized as a rectangular table of numbers, separated by blanks, with one row per line, and an equal number of elements in each row.
The save Function - Save workspace variables to disk.
SAVE FILENAME X - save variable X to filename
save test.txt magik -ASCII - save variable magik to filename text.txt with ASCII option
SAVE ... -ASCII uses 8-digit ASCII form instead of binary regardless
of file extension.
SAVE ... -ASCII -DOUBLE uses 16-digit ASCII form.
SAVE ... -ASCII -TABS delimits with tabs.
SAVE ... -ASCII -DOUBLE -TABS 16-digit, tab delimited.
Deleting rows and Columns
Then, to delete the second column of X, use
X(:,2) =