数值方法-4

And Or Not Not and
& | ~ xor
Logical Operators
And Or Not Not and & | ~ xor C=xor(A,B)
C = xor(A, B) performs an exclusive OR operation on the corresponding elements of arrays A and B. The resulting element C(i,j) is logical true (1) if A(i,j) or B(i,j), but not both, is nonzero.
Introduction to MATLAB
Prof. Zhengdong Huang
Outline
1. 2. 3. 4. 5. 6. 7. User Interfaces Variables Operators Flow Control Functions Graphic Output Miscellaneous
<, <=, >, >=, = =.
Logical Operators
1. Constants and variables 2. Operators 1. Arithmetic Operators 2. Relation Operators 3. Logic Operators 3. Controls 4. Functions
Command History – view past commands – save a whole session using diary
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User Interfaces
Two kinds of Computing Usages: 1. User interface with command input. 2. Programming using M-file.
K= x^2 Erorr: ??? Error using ==> mpower Matrix must be square. B=x*y Erorr: ??? Error using ==> mtimes Inner matrix dimensions must agree.
Operators (relational, logical)
Flow Control
1. Constants and variables 2. Operators 1. Arithmetic Operators 2. Relation Operators 3. Logic Operators 3. Controls 4. Functions
(Last time)Flow Control
Constants and Variables
1. Constants and variables 2. Operators 1. Arithmetic Operators 2. Relation Operators 3. Logic Operators 3. Controls >>x=2^3 4. Functions
• All variables are created with double precision unless specified and they are matrices.
Example: >>x=5; >>x1=2;
• After these statements, the variables are 1x1 matrices with double precision
User Interfaces
Command Input
ቤተ መጻሕፍቲ ባይዱ
User Interfaces
Command Window – type commands Current Directory – View folders and m-files
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•
•
Workspace – View program variables – Double click on a variable to see it in the Array Editor
== ~= < <= > >= & | ~ equal not equal less than less than or equal greater than greater than or equal AND OR NOT
pi 3.14159265… j imaginary unit, i same as j
Basic Arithmetic Operators
+ : Arithmetic addition - : Arithmetic subtraction * : Arithmetic multiplication / : Arithmetic division ^ : Exponent or power .* : (element by element for arrays)
• x = [1 2], y = [4 5], z=[ 0 0] A = [x y] 1 2 4 5
B = [x ; y] 1 2 4 5
C = [x y ;z] Error: ??? Error using ==> vertcat CAT arguments dimensions are not consistent.
• if
• switch
• for
statement statement loops loops statement statement
• while
• continue
if A > B disp('greater‘); elseif A < B disp('less‘); else disp('equal‘); end
1
Relation Operators
1. Constants and variables 2. Operators 1. Arithmetic Operators 2. Relation Operators 3. Logic Operators 3. Controls 4. Functions
User Interfaces
Command execution like DOS command window
Users
Run m-file programs
Input command lines
Commands provided by the system
Programs edited by users
• break
for x = 1:10 r(x) = x; end
Control Structures
• If Statement Syntax
•
t = t =1:10
1
2
3
4
5
6
7
8
9
10
•
k =
k =2:-0.5:-1
2 1.5 1 0.5 0 -0.5 -1
•
x =
B
1 5
= [1:4; 5:8]
2 6
3 7
4 8
Matrices
• x(i,j) subscription
y=x(2,3) y = 4
x= 1 2 5 1 3 2
3 4 -1
Array, Matrix
• a vector
x = 1 2 5 1 x = [1 2 5 1]
• a matrix
x = 1 5 3 2 1 2
x = [1 2 3; 5 1 4; 3 2 -1]
3 4 -1
• transpose
y = x’
y =
1 2 5 1
Long Array, Matrix
Given:
A(-2), A(0) Error: ??? Subscript indices must either be real positive integers or logicals. A(4,2) Error: ??? Index exceeds matrix dimensions.
Concatenation of Matrices
% x is a variable >>y=pi % pi is a constant >>f=cos(y) % cos() is a function
Data Types
1. Constants and variables 2. Operators 1. Arithmetic Operators 2. Relation Operators 3. Logic Operators 3. Controls You can use: Double precision 4. Functions
./ : element-by-element div .^ : element-by-element power ‘ : transpose, or complex conjugate transpose
Operators
[] concatenation
x = [ zeros(1,3) ones(1,2) ] x = 0 0 0 1 1 x = [ 1 3 5 7 9] x = 1 3 5 7 9 y = x(2) y = 3 y = x(2:4) y = 3 5 7
Functions provided by the system
Many tools provided in form of function
Graphic Simulink Signal analysis …
Language