bcpow

(PHP 4, PHP 5)

bcpowRaise an arbitrary precision number to another

Description

string bcpow ( string $left_operand , string $right_operand [, int $scale ] )

Raise left_operand to the power right_operand.

Parameters

left_operand

The left operand, as a string.

right_operand

The right operand, as a string.

scale

This optional parameter is used to set the number of digits after the decimal place in the result. You can also set the global default scale for all functions by using bcscale().

Return Values

Returns the result as a string.

Examples

Example #1 bcpow() example

<?php

echo bcpow('4.2''3'2); // 74.08

?>

Notes

Note:

bcpow() may return a result with fewer digits after the decimal point than the scale parameter would indicate. This only occurs when the result doesn't require all of the precision allowed by the scale. For example:

Example #2 bcpow() scale example

<?php
echo bcpow('5''2'2);     // prints "25", not "25.00"
?>

See Also

  • bcpowmod() - Raise an arbitrary precision number to another, reduced by a specified modulus
  • bcsqrt() - Get the square root of an arbitrary precision number

Коментарии

bcpow() only supports exponents less than or equal to 2^31-1.  Also, bcpow() does not support decimal numbers.  If you have scale set to 0, then the exponent is converted to an interger; otherwise an error is generated.

--
Michael Bailey
http://www.jinxidoru.com
2004-08-09 20:42:37
http://php5.kiev.ua/manual/ru/function.bcpow.html
Автор:
Well, if bcpow has limits, then this should work:
<?php
function bcpow_($num$power) {
   
$awnser "1";
    while (
$power) {
       
$awnser bcmul($awnser$num100);
       
$power bcsub($power"1");
    }
    return 
rtrim($awnser'0.');
}
?>
Just that $power cannot have decimal digits in it.
2005-02-11 15:58:39
http://php5.kiev.ua/manual/ru/function.bcpow.html
<?php

bcscale
(100);

/*
 * Computes the natural logarithm using a series.
 * @author Thomas Oldbury.
 * @license Public domain.
 */
function bcln($a$iter 10)
{
   
$result "0.0";
   
    for(
$i 0$i $iter$i++)
    {
       
$pow = (+ ($i));
       
$mul bcdiv("1.0"$pow);
       
$fraction bcmul($mulbcpow(bcsub($a"1.0") / bcadd($a"1.0"), $pow));
       
$result bcadd($fraction$result);
    }
   
    return 
bcmul("2.0"$result);
}

/*
 * Computes the base2 log using baseN log.
 * @note Requires above functions.
 * @author Thomas Oldbury.
 * @license Public domain.
 */
function bclog2($a$iter 10)
{
    return 
bcdiv(bcln($a$iter), bcln("2"$iter));
}

/*
 * Computes the base10 log using baseN log.
 * @note Requires above functions.
 * @author Thomas Oldbury.
 * @license Public domain.
 */
function bclog10($a$iter 10)
{
    return 
bcdiv(bcln($a$iter), bcln("10"$iter));
}


?>
2009-07-13 03:19:59
http://php5.kiev.ua/manual/ru/function.bcpow.html

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