The document discusses MATLAB commands and operators for relational operations, logical operations, if/else statements, for/while loops, and basic I/O commands. It also provides examples using these commands to solve problems such as generating matrices, determining the number of consecutive integers that sum to a value, and getting user input to check an age value.

1. MATLAB Lecture-4

2. Relational Operators Ex- a=[1 2 3]; b=[1 2 2]; a==b returns ans=1 1 0 since the last case did not match. Relational Operator Meaning < Less than <= Less than or equal > Greater than >= Greater than or equal == Equal ~= Not equal

3. Logical Operators and Functions Logical Operator Meaning & And | Or ~ Not Function Name Description ischar(x) Returns a 1 if x is a character string & 0 otherwise isfinite(x) Returns a 1 if elements of x are finite else 0 isinf(x) Returns 1 where elements of x are infinite else 0 ismember(x,y) Returns 1 when elements of x are also in y else 0 isreal(x) Returns 1 whenever the elements of x have no imaginary part and a 0 otherwise

4. If Statement Simple if Statement if logical expression1 statement group1 end Nested if statement if logical expression1 statement group1 if logical expression2 statement group2 end statement group3 end statement group4

5. If else statements if else statement if logical expression1 statement group1 else statement group2 end if elseif statement if logical expression1 statement group1 elseif logical expression2 statement group2 end

6. If elseif else statement if logical exression1 statement group1 elseif logical expression2 statement group2 elseif logical expression3 statement group3 elseif logical expression4 statement group4 else statement group5 end

7. Switch-case statement switch switch expression case value1 … .. … ..{ Group 1 of Commands} case value1 … .. … ..{ Group 2 of Commands} otherwise … .. … ..{ Group 3 of Commands} end

8. Assignment-1 Using a MATALAB function file write a code for A/D converter (if else) where ‘x’ is i/p and ‘y’ is digital o/p governed by following eq. y=0 x<-2.5 =1 -2.5 < x<-1.5 =2 -1.5 < x<-0.5 =3 -0.5 < x<0.5 =4 0.5 < x<1.5 =5 1.5 < x<2.5 =6 2.5 < x<3.5 =7 x > 3.5 Test for condition with amplitudes -1.25, 2.57 and 6.

9. Solution using if else function y_dig=bitatd_(x-analog) if x-analog<-2.5 y_dig=0; elseif x-analog>=-2.5 & x-analog<-1.5 y_dig=2; …… .(so on) elseif x-analog>=2.5 y_dig=6; else y_dig=7; end

10. For loops It allows a group of statements to be repeated a fixed number of times. for index = expression statement group X end expression may be of the form m:n or m:i:n where m is beginning value, n is ending value and i is increment.

11. Assignment-2 Find out the squares of integers from 1 to 100 and show their sum. Fill a 10 by 20 matrix with unity to demonstrate the use of nested ‘for’ operations

12. Solution sum=0; for i=1:100 sum=sum+i^2; end sum n=10; m=20; for i=1:n for j=1:m b(i,j)=1; end end b

13. While Loops A while loop allows one to repeat a group of statements as long as the specified condition is satisfied. while expression1 statement group1 end statement group2

14. Assignment-3 Determine the number of consecutive integers that when added together will give a value equal or just less than 210.

15. Solution int=1; int_sum=0; max_val=210; while int_sum<max_val int_sum=int_sum+int; int=int+1; end last_int=int if int_sum==max_val num_int=int-1 tt_int_ct=int_sum elseif int_sum>max_val num_int=int-1 tt_int_ct=int_sum-last_int end

16. Some basic I/O commands Command Description break Exits while or for loop disp Displays text or matrix echo Displays m-files during execution error Displays error messages format Switches output display to a particular format fprintf Displays text and matrices and specifies format for printing values input Allows user input keyboard Invokes the keyboard as an m-file pause Causes an m-file to stop executing, pressing any key causes resumption of program execution

17. Assignment-4 Using disp Command generate the following matrix:- 1 0 0 0 1 0 0 0 1 The above matrix should be generated using (a) Iterative method (b) Basic MATALAB command in one line. 2. Write a User friendly MATLAB program which should enter the age of the user and display an error message if age<0 and ask the user again to enter the age.

18. Solution 1 a.) clc; clear all; close all; for i=1:3 for j=1:3 if i==j a(i,j)=1; else a(i,j)=0; end end end b.) disp(eye(3,3))

19. Solution 2 clc; clear all; close all; x=input(‘Enter your age’); if x<0 error(‘Wrong age entered’); end x=input(‘Enter your age’);