randrandom real number procedure

Syntax   rand (var r : real)

Description   The rand statement is used to create a pseudo-random number in the range zero to one. For example, if x is a real number, after rand(x), x would have a value such as 0.729548 or 0.352879.

Example   This program repeatedly and randomly prints out Hi ho, hi ho or It's off to work we go.

        var r : real
            rand ( r )
            if r > 0.5 then
                put "Hi ho, hi ho"
                put "It's off to work we go"
            end if
        end loop
Details   The rand statement sets its parameter to the next value of a sequence of pseudo-random real numbers that approximates a uniform distribution over the range 0<r <1.

Each time a program runs, rand uses a different pseudo-random number sequence. To get the same sequence (use Rand.Set).

To use several sequences of repeatable pseudo-random number sequences, use the randseed and randnext procedures.

In many languages, rand would be a function rather than a procedure. It has been designed as a procedure in Turing to respect the mathematical idea that every call to a function using the same arguments (or no arguments at all) should return the same value. If rand were a function, this would not be true.

See also   randint, randomize, randseed and randnext.

See also predefined unit Rand.