Checking for value within boundaries - matlab

Question

I'm trying to create a function that would verify if a value is within chosen boundaries and if it's not, the user must retry until verification.
I wanted to know why my code skips the if condition for any given value and it returns me for the input prompt : "Error: Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error."
A=limit(5pi/6,-pi/2,pi/2) for example jumps directly to the else condition while it's true for the if condition
Here is my code :
function alpha = limit(pos,min,max)
if (pos >= max) && (pos <= min)
alpha=pos;
else
while pos >= max || pos <= min
prompt = 'Enter value between max and min';
alpha = input(prompt);
end
end
end

Answer 1

The function first checks whether pos is both greater than or equal to max and less than or equal to min.
I expect you intend max to be greater than min. Therefore, the if line should be:
if (pos <= max) && (pos >= min)
I assume your val_max/val_min are typos (and should be max/min) Then, your while loop depends on the value of pos. But pos is never updated in the loop, so your loop is just going to iterate forever.
You need to update pos inside the while loop for this to work. Try something like this:
function alpha = limit(pos,min,max)
while pos > max || pos < min
prompt = 'Enter value between min and max';
pos = input(prompt);
end
alpha = pos;
end