how to display 'Not a number, try again'

How do I display 'not a number, try again' when a word has been entered (eg. the letter a), without prducing error messages?

x = input('type a number: ')
t=isstring(x)
while t =1 
    disp('Not a number, try again')
    x = input('type a number: ')
end
y = x*3
disp(y)

Answer 1

[Walter Roberson]

msg = 'type a number: ';
while true
  xs = input(msg, 's');
  x = str2double(xs);
  if ~isnan(x); break; end
  disp('Not a number, try again')  
end

[Cross Category]

Thanks!

[Walter Roberson]

; is a statement separator that indicates that the expression before it is to be executed and any default display of results is not to be done. You can can also use comma instead, and when you do, the default output will appear.

There is a completely different use as well. Inside [] or {} indicates that a new row of values is to be started, such as [1 2;3 4] to define the array

1 2
3 4

[Cross Category]

Thank you so much, right after I asked the question, I realised I would google it. So I deleted the question.

But thank you for the detailed explaination.