RANDOM( )

Topic group Related topics

Returns a pseudo-random number between 0 and 1 exclusive (never 0 and
never 1). Same as RAND( )

Syntax

RANDOM([<expN>])

<expN>

The number with which you want to seed RANDOM( ).

Description

Computers cannot generate truly random numbers, but you can use RANDOM( ) to generate a series of numbers that appear to have a random distribution. A series of pseudo-random numbers relies on a seed value, which determines the exact numbers that appear in the series. If you use the same seed value, you get the same series of numbers.

Pseudo-random numbers, when considered as a whole series, appear to be random; that is, you cannot tell from one number what the next will be. But the first number in the series is related to the seed value. Therefore, you should seed RANDOM( ) only once at the beginning of each series, like before simulating a card shuffle or randomly assigning work shifts. Seeding during a series defeats the design of the random number generator.

If you specify a positive <expN> value, RANDOM( ) uses that <expN> as the seed value, so a positive value should be used for testing, since the numbers will be the same each time. If <expN> is negative, RANDOM( ) uses a seed value based on the number of seconds past midnight on your computer system clock. As a result, a negative <expN> value most likely will give you a different series of random numbers each time.

If you don't specify <expN>, or use zero, RANDOM( ) returns the next number in the series.

When dBASE Plus first starts up, the random number generator is seeded with a fixed internal seed value of 179757.

Use SET DECIMALS to set the number of decimal places RANDOM( ) displays.