Prompt for user input.
INPUT('How many apples') gives the user the prompt in the
text string and then waits for input from the keyboard.
The input can be any MATLAB expression, which is evaluated,
using the variables in the current workspace, and the result
returned as the value of the function.
INPUT('What is your name','s') gives the prompt in the text
string and waits for character string input. The typed input
is not evaluated; the characters are simply returned as a