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# frandom(-F)

Generates a random floating-point number F in the range <0, 1>.
F
Floating-point number or variable.

## Description

frandom/1 unifies F with a random floating-point number between 0 and 1. The code is taken from random2.c by John Burton, available from the net. Part of original comment:

``` *
* PMMMLCG - Prime Modulus M Multiplicative Linear Congruential Generator   *
*  Modified version of the Random number generator proposed by             *
*  Park & Miller in "Random Number Generators: Good Ones Are Hard to Find" *
*  CACM October 1988, Vol 31, No. 10                                       *
*   - Modifications proposed by Park to provide better statistical         *
*     properties (i.e. more "random" - less correlation between sets of    *
*     generated numbers                                                    *
*   - generator is of the form                                             *
*         x = ( x * A) % M                                                 *
*   - Choice of A & M can radically modify the properties of the generator *
*     the current values were chosen after followup work to the original   *
*     paper mentioned above.                                               *
*   - The generator has a period of 0x3fffffff with numbers generated in   *
*     the range of 0 < x < M                                               *
*   - The generator can run on any machine with a 32-bit integer, without  *
*     overflow.                                                            *
```

### Modes and Determinism

• frandom(-) is det

### Exceptions

(5) type error
F is instantiated, but not to a floating-point number.

## Examples

```Success:
?- frandom(F1), frandom(F2).
F1 = 0.900086582
F2 = 0.0795856342
yes.

?- seed(1), frandom(F).
F = 2.2477936e-05
yes.
?- seed(1), frandom(F).
F = 2.2477936e-05
yes.

Fail:
frandom(123.45).

Error:
frandom(1234).          (Error 5).
```