Branches

 Loops permit us to execute a sequence  They differ in how the repetition is Compute the average of n values entered by the user. The number of values (n) wil be specified by n = input('Enter the number of values: ');counter = 0; total = 0;while (counter < n ) total = total + x; counter = counter + 1;endif (n > 0) avg = total / counter; disp(['The average is ' num2str(avg)]);end Compute the average of values entered by the user. A negative value indicates the end of the input.
counter = 0;total = 0;x = input('Enter the first value: ');while (x >= 0 ) counter = counter + 1; total = total + x; x = input('Enter the next value: ');endif (counter > 0) avg = total / counter; disp(['The average is ' num2str(avg)]);end Example: “Change case” Change the case of letters in a sentence.
k = 1;while (k <= length(s)) if (s(k) >= 'A') & (s(k) <= 'Z') new_s(k) = char('a' + (s(k) - 'A')); elseif (s(k) >= 'a') & (s(k) <= 'z') new_s(k) = char('A' + (s(k) - 'a')); else new_s(k) = s(k); end k = k + 1;endnew_s “for” Loop Statements are executed a specified number  No of repetitions is known before the loop starts  Expression is usual y a vector in shortcut Using “for” loop, compute the average of n values
entered by the user. The number of values (n) wil be n = input('Enter the number of values: ');total = 0;for counter = 1 : n total = total + x;endif (counter > 0) avg = total / counter; disp(['The average is ' num2str(avg)]);end Example: “Factorial calculation” Calculate the factorial (N!) of an integer N; the factorial of negative integers is not  N = input('Enter a non-negative integer: '); if N < 0 disp(['It is a negative integer']);else result = 1; for i = 1 : N, result = result *i; end disp([num2str(N) '! = ' num2str(result)]);  Write a program that finds the first  A positive integer n is a perfect number if the sum of its positive divisors excluding n  e.g., 28 is a perfect number; 1+2+4+7+14=28 Example: “Perfect numbers”counter = 1;no = 1; while counter <= 3
total = 0;
for ii = 1 : no/2
if mod(no,ii) == 0
total = total + i ;
if no == total
perfect_nos(counter) = no; counter = counter + 1; end
no = no + 1;
end
fprintf('The first three perfect numbers are ')
for counter = 1 : 3
fprintf('%d ',perfect_nos(counter));
end
 Compute the multiplication of two matrices.
 If A is an m-by-n matrix and B is an n-by-p matrix, their product is an m-by-p matrix C which is given  The matrix multiplication is defined between two matrices only if the number of columns of the 1st matrix is the same as the number of rows of the Example: “Matrix multiplication”[row_A,column_A] = size(A);[row_B,column_B] = size(B); if column_A ~= row_B
disp('Matrix dimensions must agree');
else
for ii = 1 : row_A
for jj = 1 : column_B
C(ii,jj) = 0;
for k = 1 : column_A
C(ii,jj) = C(ii,jj) + A(ii,k) * B(k,jj);
end
end
end
end
 Use indentation to improve the readability of  Never modify the value of a loop index inside  Al ocate al arrays used in a loop before executing  If it is possible to implement a calculation either with a loop or using vectors, always use vectors  Use built-in MATLAB functions as much as possible C4(i ,jj) = C4(ii,jj) + A(ii,k) * B(k,jj); C2(i ,jj) = C2(i ,jj) + A(i ,k) * B(k,jj); t1 = 0.0020, t2 = 5.0160, t3 = 0.1100, t4 = 4.9060 end fprintf( 'i = %d\n', i );enddisp( 'End of loop' ); Write a program in which the user tries to guess a number picked by the computer. The number is picked between 1 and 10 and the user has at most three tries.
num = fix(10 * rand + 1);if num == 11, num = 10; end for tries = 1:3,
guess = input( 'Your guess? ' );
if ( guess == num ),
disp( 'Congratulations!' );
break;
end
end
if ( guess ~= num ),
disp( 'You could not guess correctly' );
end
Compute the perimeter of a polygon whose size is specified by N = input('Enter the polygon size: ');
if N < 3
disp('It is not a polygon');
else
i = 1; perimeter = 0;
while (i <= N)
edge_length = input([‘Length of edge ' num2str(i ) ': ']);
if edge_length <= 0
disp('The length should be positive');
continue;
end
perimeter = perimeter + edge_length;
i = i + 1;
end
end
disp(['Perimeter: ' num2str(perimeter)]);

Source: http://www.cs.bilkent.edu.tr/~duygulu/Courses/CS111/Notes/Loops.pdf