I need help determining and displaying the number of steps it takes to complete this loop when any integer is entered.

so I have figured out how to write the while loop I need. It looks like this:

b=0;
b=input('Enter an integer greater than 1:');
while b>1
  if mod (b,2)==0;
      b=b/2;
  else mod(b,2)~=0;
      b=(b*3)+1;
  end 
end

It takes any given integer, multiplies it by 3 then adds 1 if it is odd. It divides the number by 2 when it is even. I need to represent the number of steps it takes this loop to get to the number 1, which is where it ends. I've tried "b=length(b)' and it just says b=1. I cannot figure out how to write a code to display how many steps it takes to reach 1 when an integer is given. Example, if the user enters "3" the steps would be 3 → 10 → 5 → 16 → 8 → 4 → 2 → 1 If the user were to enter this particular integer, I would need my output to be "s=7."

[Stephen23]

Note that you do not need both of these conditions:

if mod (b,2)==0;
   ...
else mod(b,2)~=0;
   ...
end

If mod(b,2)==0 then the first case will run. Clearly all remaining cases must be not equal to zero, so all you need is:

if mod(b,2)==0
   ...
else
   ...
end

I also removed the semi-colons, which are not required after if or switch conditions: the semi-colon can be used to suppress results of an operation, but conditions are never displayed.

[Walter Roberson]

My system is busy at the moment, but I wonder what mod(inf,2) is ? Potentially it is neither 0 nor 1.

Answer 1

[Stephen23]

You just need to add a counter variable, here I used cnt:

str = input('Enter an integer greater than 1: ','s');
num = str2double(str); % safer for INPUT to return a string!
cnt = 0;
while num>1
    cnt = cnt+1;
    if mod(num,2)
        num = num*3+1;
    else
        num = num/2;
    end
end
disp(cnt)

And tested:

>> temp0 % or whatever the name of your script is.
Enter an integer greater than 1: 3
    7

[Kevin Smith]

Thank you!