To accept two numbers from the user and display perfect numbers between these two numbers.

hi,

how do i write the code for the above? how do i continue from here. thank you very much.

clc
num1 =input('Enter num1 value ');
num2 =input('Enter num2 value ');

Answer 1

[Walter Roberson]

num1 =input('Enter num1 value ');
num2 =input('Enter num2 value ');
for n = num1 : num2
  if isperfectnumber(n)
    disp(n);
  end
end

Now you just have to write the function isperfectnumber() that returns true if its input is a perfect number.

[Josaiah Ang]

hi Walter, i got this error message. Could you be advise?

Undefined function or variable 'isperfectnumber'.

Error in Untitled1 (line 4)
  if isperfectnumber(n)

[Walter Roberson]

As I wrote above:

"Now you just have to write the function isperfectnumber() that returns true if its input is a perfect number."

[Josaiah Ang]

Thank you Walter.

i require some help on writing the function to determine the perfect number.

I have just only started using matlab for 2 weeks. Hope you could help me. Thank you.

Answer 2

[Image Analyst]

Here's something a little more user friendly and robust:

% Ask user for two floating point numbers.
defaultValue = {'45.67', '78.91'};
titleBar = 'Enter a value';
userPrompt = {'Enter floating point number 1 : ', 'Enter floating point number 2: '};
caUserInput = inputdlg(userPrompt, titleBar, 1, defaultValue);
if isempty(caUserInput),return,end; % Bail out if they clicked Cancel.
% Convert to floating point from string.
usersValue1 = str2double(caUserInput{1})
usersValue2 = str2double(caUserInput{2})
% Check for a valid number.
if isnan(usersValue1)
    % They didn't enter a number.  
    % They clicked Cancel, or entered a character, symbols, or something else not allowed.
  % Convert the default from a string and stick that into usersValue1.
    usersValue1 = str2double(defaultValue{1});
    message = sprintf('I said it had to be a number.\nI will use %.2f and continue.', usersValue1);
    uiwait(warndlg(message));
end

I don't of any real world uses for a perfect number, so I assume that this is homework. So you can write that algorithm, like Walter said.

Answer 3

[Roger Stafford]

As part of your procedure in identifying a perfect number you need to determine the sum of all the divisors of a given integer, n, except n itself. This will find it for you:

N = 1:n-1;
s = sum(N(mod(n,N)==0));