The RAN function is a general random number generator of the multiplicative congruential type. The result is a floating-point number that is uniformly distributed in the range between 0.0 inclusive and 1.0 exclusive. The call to RAN takes the following form:

y = RAN (i)

y

Is set equal to the value associated, by the function, with the argument i. The argument i is called the seed. It must be an INTEGER*4 variable or INTEGER*4 array element.

The argument should initially be set to a large, odd integer value. The RAN function stores a value in the argument that it later uses to calculate the next random number.