matlab programming for engineers
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CH3: BRANCHING STATEMENTS
Mechanical Engineering Department
MATLAB PROGRAMMING FOR ENGINEERS
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Matlab Programming for Engineers Matlab Programming for Engineers
Dr. Nidal Farhat
Introduction to MatlabIntroduction to Matlab Matlab Basics Matlab Basics Branching StatementsBranching Statements Loops Loops User Defined Functions User Defined Functions Additional Data Types Additional Data Types Input/Output Functions Input/Output Functions Simulink Toolbox Simulink Toolbox Important Toolboxes (if time is available) Important Toolboxes (if time is available)
CH3: BRANCHING STATEMENTS
Mechanical Engineering Department
MATLAB PROGRAMMING FOR ENGINEERS
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OBJECTIVES
The Logical Data Type Relational Operators (==, ~=, >, < , >=, <=) Logic Operators (&, &&, |, ||, xor, ~) Logical Functions (ischar, isempty, ….) Branches
(if-else) Statement switch Statement try-catch Statement
Additional Plotting Features
CH3: BRANCHING STATEMENTS
Mechanical Engineering Department
MATLAB PROGRAMMING FOR ENGINEERS
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THE LOGICAL DATA TYPE (true, false)
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RELATIONAL OPERATORS (==, ~=, >, < , >=, <=)
Some relational operations and their results
CH3: BRANCHING STATEMENTS
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MATLAB PROGRAMMING FOR ENGINEERS
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RELATIONAL OPERATORS (==, ~=, >, < , >=, <=)
Compare array by a value
Compare array by another one (of the
same size)
Be careful because of roundoff errors
CH3: BRANCHING STATEMENTS
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LOGIC OPERATORS
Operator Operation& Logical AND (scalar/array, both sides evaluation)
&& Logical AND (scalar, left then right side evaluation)
| Logical inclusive OR (scalar/array both sides evaluation)
|| Logical inclusive OR (scalar, left then right side evaluation)
xor Logical exclusive OR~ Logical NOT
CH3: BRANCHING STATEMENTS
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MATLAB PROGRAMMING FOR ENGINEERS
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LOGIC OPERATORS
EXAMPLE
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LOGICAL FUNCTIONS
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QUIZ!
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Branches:
a) if Statement
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BRANCHES (if-STATEMENT)
Optional
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BRANCHES (if-STATEMENT)
Example: Write a program that determine whether a quadratic equation:
has real (identical/different) or complex roots. (Use input command for entering the coefficients (a,b,c) and disp commands to display the output).
Write a program that calculates the roots in each case. (Use input command for entering the coefficients of the equation and disp commands to display the output).
Test the program on the following equations:
CH3: BRANCHING STATEMENTS
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MATLAB PROGRAMMING FOR ENGINEERS
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BRANCHES (if-STATEMENT)
Example: evaluating a Function of Two Variables
Test it using the following (x,y) values:
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BRANCHES (if-STATEMENT)
Nested if-Statements
It is preferable to use if-else-end statement whenever is possible
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Branches:
b) switch Statement
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BRANCHES (switch-STATEMENT)
The switch statement syntax is a means of conditionally executing code. In particular, switch executes one set of statements selected from an arbitrary number of alternatives.
The switch_expr and case_expr may be a scalar or a string
Optional
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BRANCHES (switch-STATEMENT)
Remarks: The case expression could be more than one enclosed by {}
At most one code block can be executed. If the switch_exp matches more than case_exp the first one is executed.
CH3: BRANCHING STATEMENTS
Mechanical Engineering Department
MATLAB PROGRAMMING FOR ENGINEERS
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BRANCHES (switch-STATEMENT)
Example:
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BRANCHES (switch-STATEMENT)
Example:
Example
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BRANCHES (switch-STATEMENT)
Example
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Branches:
b) try/catch Statement
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BRANCHES (try/catch)
The try/catch statement is designed to trap errors. In MATLAB when an error is encountered while running the program
the program execution is aborted. Use try/catch statement to run a part of the program susceptible to
produce error when executed. MATLAB will try to execute this part. If an error is produced, then instead of aborting, it executes the part of the program found in the catch statement.
If no error is produced in the try block, the catch block will not be executed.
The programmer can handle errors in the program without causing the program to stop.
CH3: BRANCHING STATEMENTS
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BRANCHES (try/catch)
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BRANCHES (try/catch)
Example
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fprintf command
fprintf(format,data)
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Additional plotting features
Example f(x) = sin(x), from -2π to 2π
Then restrict the axes to the region 0 ≤ x ≤ π, and 0 ≤ y ≤ 1
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Additional plotting features
Plotting Multiple Plots on the Same Axes
OR
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Additional plotting features
Creating Multiple Figures
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Additional plotting features
Subplots Subplot(m,n,p) ≡ creates mxn subplots in the current figure (array of
subplots), m rows and n columns. p is the current subplot.
p=1 p=2
p=4 p=[5 6]
p=3
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Additional plotting features
Enhanced Control of Plotted Lines
plot(x,y,'PropertyName',value,…)
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Additional plotting features
Enhanced Control of Plotted Lines Example,
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Additional plotting features
Enhanced Control of Text Strings
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Additional plotting featuresEn
hanc
ed C
ontr
ol o
f Tex
t Str
ings
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Additional plotting features
Enhanced Control of Text StringsExamples:
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Additional plotting features
Polar Plotspolar(theta,r)
Example,
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Additional plotting features
Polar Plotspolar(theta,r)
Solution:
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