warning about units of parameters

ı have started to create such a code shown below. but ı need to do something whıch ı couldnt until now. what can ı add on my code to make it unit sensitive? because ı want to use ''meter'' and what if user enters milimeter the program should warn him to fix it and then continue. thanks in advance...

 
l=input('enter a value for length:'); %bearing length (m)
d=input('enter a value for diameter:') ;  %journal diameter (m)
r=d/2;                              %radius (m)
c=input('enter a radial clearance:'); % radial clearance (m)
T1=input('assign an inlet temperature:'); %inlet temperature (celcius)
delta_T=input('enter temperature rise value:'); %assumed temperature rise (celcius)
W=input('enter a radial load on journal:');     %radial load on journal (N)

Answer 1

[Walter Roberson]

You will want to use the 's' option of input() to receive the user response as text, and pick out any user units as text, check the unit, and if the unit is okay, convert the numeric part.

If you want to do units conversion you might find it easiest to use Symbolic Toolbox symunit https://www.mathworks.com/help/symbolic/symunit.html

[matlab coder]

thanks for this useful toolbox but ı want to write a code that will warn the user when he or she enters differents units. for example if ı want to use meter and accidentaly use centimeter the program should warn me to change my unit.

[Walter Roberson]

known_units = {'m', 'mm', 'kg', 'C', 'N', 'Hz'};

for K = 1 : 5
    try
        if ispc()
          l = input('enter a value for length: ', 's'); %bearing length (m)
        else
          if rand < 1/3
              bads = {'ask Bob', '3.141 F'};
              l = bads{randi(length(bads))};
          else
            l = sprintf('%e%s', randn()*10, known_units{randi(length(known_units))});
          end
        end
        fprintf('Input was: "%s"\n', l);
        
        L = l;
        l_unit = '';
        l_unit_pos = regexp(l, '\D+$', 'start');
        if ~isempty(l_unit_pos)
           l_unit = strtrim(l(l_unit_pos:end));
           l = l(1:l_unit_pos-1);
           if ~ismember(l_unit, known_units)
             error('Unknown unit found in entry "%s"', L);
           end
        end
        lnum = str2double(l);
        if isnan(lnum)
           error('Bad number found in entry "%s"', L);
        end
        
        fprintf('number was %g unit was "%s"\n', lnum, l_unit);
    catch ME
        disp(ME.message)
    end
end

Input was: "-7.602150e+00kg"

number was -7.60215 unit was "kg"

Input was: "ask Bob"

Unknown unit found in entry "ask Bob"

Input was: "3.141 F"

Unknown unit found in entry "3.141 F"

Input was: "1.528264e+01mm"

number was 15.2826 unit was "mm"

Input was: "-1.041360e+00N"

number was -1.04136 unit was "N"

[matlab coder]

thank you