MATLAB question

[nflasky]

I had to write a program for my MATLAB class to sort a user given 5x5 matrix, and then sort this matrix by either rows or columns and give the CPU time.  I seem to have everything working out fine.  However, I am still trying to figure out how to prevent the user from entering a complex number or a string.  I know MATLAB has a built in isreal function that I may be able to use.  Just wondering if anybody could give me some advice.  My code is below:

 

for i = 1:5 

for j = 1:5 

str = ['Enter element in row ' num2str(i) ', col ' num2str(j) ': ']; 

matrix(i,j) = input(str); 

end 

end 

choice = menu('Enter row or column','Row', 'Column');

switch choice

   case 1

      answer = sort(matrix, 2, 'ascend');

      disp('The sorted matrix by columns is: ')

      disp(answer)

      disp('The original matrix is: ')

      disp(matrix)

   case 2 

      disp('The sorted matrix by rows is: ')

      sort(matrix)

      disp('The original matrix is: ')

      disp(matrix)

 end

      cpu = cputime;

      disp('Your CPU time is: ') 

      disp(cputime)

      

[rashdanml]

The ideal spot to check would be using the isreal function as a conditional before assigning the value to matrix(i,j)

 

if (isreal(inputval))> assign valueelse > prompt to re-enter valueend

 

Or something along those lines. You may need to throw the above conditional inside a while (true) loop (to keep the loop going for as long as a complex number is being entered), as well as a break statement after assigning matrix(i,j) = input(str)