Post on 14-Apr-2016
description
Structural Analysis
Lec-2
Contents Matrices Contd…
Matrix Indexing
Functions
1. Scalars
2. Vectors
Operators (Relation + Logical)
Plotting
Some useful Matrices
eye Identity Matrix
zeros A matrix of zeros
ones A matrix of ones
diag Creating or extracting diagonals
rand Random matrix
MATLAB Functions
Some Predefined Matrices Random matrices
Matrix of zeros
Matrix of ones
Identity matrix
Diagonal matrix
rand(3)
rand(3,4)
Zeros(2,3)
Ones(10,1)
Eye(3)
diag(3,2)
Matrix Indexing
Advanced Indexing
Submatrices A=rand(5)
A (2 , 3)
A(1,end)
A(1:2 , 2:3)
A(1 , :)
A(7)
% Define Matrix
Specifying an element
Specifying contiguous submatrix
To specify entire first row
=A(2,2)
Row
Column
Scalar Functions Some MATLAB functions applied to:
a. Scalars only
b. To all elements of vectors and matrices
A=rand(3,4)
b=sqrt(A)
C=cos(A)
Note: We may extract a submatrix and then use these
functions
Vector Functions Some MATLAB functions that operate on vectors only
Matrix Functions Important Matrix Functions
A=rand(3)
B=eig(A)
Sometimes such functions may use more than one
output function
[V,D]=eig(A)
Matrix whose columns are eigen vectors
Matrix whose diagonal values represents eigen values
Matrix Operations
Matrix Addition
Matrix Subtraction
Matrix mutiplication
C=A+B
C=A-B
C=A*D
Operators Some relation operators
Logical Operators
• The result is either 0 or 1.
• Zero…if it is false
• One…If it is true
Operators Precedence
Plotting For 2D plots
For 3D plots….use Plot3
Exercise