Bcmath php как включить

Вычисления над числами с произвольной точностью BCMath

This extension is an interface to the GNU implementation as a library of the Basic Calculator utility by Philip Nelson; hence the name.

8 years ago

Note that when you use implementation of factorial that ClaudiuS made, you get results even if you try to calculate factorial of number that you normally can’t, e.g. 2.5, -2, etc. Here is safer implementation:
/**
* Calculates a factorial of given number.
* @param string|int $num
* @throws InvalidArgumentException
* @return string
*/
function bcfact ( $num )
if (! filter_var ( $num , FILTER_VALIDATE_INT ) || $num <= 0 ) throw new InvalidArgumentException ( sprintf ( 'Argument must be natural number, "%s" given.' , $num ));
>

for ( $result = ‘1’ ; $num > 0 ; $num —) $result = bcmul ( $result , $num );
>

10 years ago

Needed to compute some permutations and found the BC extension great but poor on functions, so untill this gets implemented here’s the factorial function:

/* BC FACTORIAL
* n! = n * (n-1) * (n-2) .. 1 [eg. 5! = 5 * 4 * 3 * 2 * 1 = 120]
*/
function bcfact ( $n ) $factorial = $n ;
while (— $n > 1 ) $factorial = bcmul ( $factorial , $n );
return $factorial ;
>

print bcfact ( 50 );
//30414093201713378043612608166064768844377641568960512000000000000
?>

6 years ago

Useful function for bcround

function getBcRound($number, $precision = 0)
$precision = ($precision < 0)
? 0
: (int) $precision;
if (strcmp(bcadd($number, ‘0’, $precision), bcadd($number, ‘0’, $precision+1)) == 0) return bcadd($number, ‘0’, $precision);
>
if (getBcPresion($number) — $precision > 1) $number = getBcRound($number, $precision + 1);
>
$t = ‘0.’ . str_repeat(‘0’, $precision) . ‘5’;
return $number < 0
? bcsub($number, $t, $precision)
: bcadd($number, $t, $precision);
>

function getBcPresion($number) $dotPosition = strpos($number, ‘.’);
if ($dotPosition === false) return 0;
>
return strlen($number) — strpos($number, ‘.’) — 1;
>

var_dump(getBcRound(‘3’, 0) == number_format(‘3’, 0));
var_dump(getBcRound(‘3.4’, 0) == number_format(‘3.4’, 0));
var_dump(getBcRound(‘3.56’, 0) == number_format(‘3.6’, 0));
var_dump(getBcRound(‘1.95583’, 2) == number_format(‘1.95583’, 2));
var_dump(getBcRound(‘5.045’, 2) == number_format(‘5.045’, 2));
var_dump(getBcRound(‘5.055’, 2) == number_format(‘5.055’, 2));
var_dump(getBcRound(‘9.999’, 2) == number_format(‘9.999’, 2));
var_dump(getBcRound(‘5.0445’, 5) == number_format(‘5.044500’, 5));
var_dump(getBcRound(‘5.0445’, 4) == number_format(‘5.04450’, 4));
var_dump(getBcRound(‘5.0445’, 3) == number_format(‘5.0445’, 3));
var_dump(getBcRound(‘5.0445’, 2) == number_format(‘5.045’, 2));
var_dump(getBcRound(‘5.0445’, 1) == number_format(‘5.05’, 1));
var_dump(getBcRound(‘5.0445’, 0) == number_format(‘5.0’, 0));//
var_dump(getBcRound(‘5.04455’, 2) == number_format(‘5.045’, 2));
var_dump(getBcRound(‘99.999’, 2) == number_format(‘100.000’, 2));
var_dump(getBcRound(‘99.999’) == number_format(‘99.999’, 0));
var_dump(getBcRound(‘99.999’, ‘a’) == number_format(‘99.999’, 0));
var_dump(getBcRound(‘99.999’, -1.5) == number_format(‘99.999’, 0));
var_dump(getBcRound(‘-0.00001’, 2) == number_format(‘-0.000’, 2));
var_dump(getBcRound(‘-0.0000’, 2) == number_format(‘0’, 2));
var_dump(getBcRound(‘-4.44455’, 2) == number_format(‘-4.445’, 2));
var_dump(getBcRound(‘-4.44555’, 0) == number_format(‘-4.5’, 0));
var_dump(getBcRound(‘-4.444444444444444444444444444444444444444444445’, 0) == number_format(‘-4.5’, 0));

9 years ago

It’s worth noting that this library is named very wrongly.

It may be called ‘Binary Calculator’, but what you’re getting is a decimal calculator that can represent base-10 fractions accurately.

6 years ago

Useful function for bcround

function getBcPresion($number) $dotPosition = strpos($number, ‘.’);
if ($dotPosition === false) return 0;
>
return strlen($number) — strpos($number, ‘.’) — 1;
>

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