How to make a loop of a calculator that keeps asking until the input is zero/nothing?

Your solution must prompt user to input the option (DR or RD). If the option is DR, then ask for angle in degrees and the program displays the equivalent radians. If the option is RD then ask for angle in radians then the program displays the equivalent degrees. Your program should able to accept both scalar and matrix input. The script should keep running until no number is provided to convert. [The function isempty will be useful here]

i only got this far and there seems to be a problem with my code (when you type a number, it shows 2-4 answer)

choice = menu ('Choose the conversion you want to calculate','DR','RD','Other');

  if choice == 1;
    fprintf('You have choosen a Degree to Radian conversion'); 
    fprintf('\n');
    num = input ('Enter an angle in degrees: ', 's');
    result = (num) * pi / 180;
    no = str2double(result);
  elseif choice == 2;
    fprintf('You have choosen a Radian to Degree conversion');
    fprintf('\n');
    num = input ('Enter a number in Radian: ', 's');
    result = (num) * 180 / pi;
    no = str2double(result);
  else
    fprintf('Error mag\n');
    end

 
fprintf('The result of the conversion is %d\n', no);

Answer 1

[Rik]

You forgot to convert the result to a number, so it is a char array.

%radian = input ('Input a number: ', 's');
%Input a number: 1.2
%  this result in:
radian='1.2';

radian=str2double(radian);

[JJD]

i have re-edit the code, is it correct? and i don't understand what is 'str2double' ?

i have inserted the str2double, but now the answer NaN

[Rik]

You should read the documentation for input more carefully, read the documentation for str2double, and learn to use breakpoints to step through your code line by line so you can see the effect every line has.

Your call to input results in a char array, not a number.

You can use str2double to convert a char array that describes a number to an actual number (i.e. it turns '1.2' into 1.2). That way you can perform calculations with the user input.

[JJD]

ooohh, ok thank you for your help

[Rik]

You're welcome. If this answer solved your issue, please consider marking it as accepted answer. If not, feel free to comment with your remaining issues.

[Ken L]

Hi Rik, since this question require isempty function, may I know where to insert the isempty function? Thank you.

[Rik]

What do you think? Your program should keep going until the user doesn't provide an input. How would you detect that?