bcFact(...) - PHP Science Labs

PHPSL Function: bcFact( )

bcFact ($IntN)

Dependencies: NONE

This function computes the simple arbitrary-precision factorial of any positive integer (N), where its factorial (N!) is simply the product of all of the integers from 1 to (N) multiplied together, the exception being 0!, which is equated to 1, by definition.

Because factorial values rapidly become extremely large, this function has a built-in limit of N = 9999, however this limit can be removed. Factorials of integers over 10000 can take several seconds to compute and a script time-out may be possible if too extreme.

∏ n = 1 N n = 1 ⋅ 2 ⋅ 3 ⋅ . . . ⋅ N

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function bcFact ($IntN='0') { $N = trim($IntN); if (!is_numeric($N) or $N < 0 or $N > 9999) {return FALSE;} $n = bcadd($N, '0'); $P=1; for ($i=1; $i <= $n; $i++) {$P = bcmul($P, $i);} return $P; }
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EXAMPLE call results:
```
   print bcFact(5);
// =--> 120


   print bcFact(10);
// =--> 3628800


   print bcFact(41);
// =--> 33452526613163807108170062053440751665152000000000
```

Jay Tanner - 2024