note 94610 added to ref.bc

Some useful bcmath functions: <?php /* * Computes the factoral (x!). * @author Thomas Oldbury. * @license Public domain. */ function bcfact($fact, $scale = 100) { if($fact == 1) return 1; return bcmul($fact, bcfact(bcsub($fact, '1'), $scale), $scale); } /* * Computes e^x, where e is Euler's constant, or approximately 2.71828. * @author Thomas Oldbury. * @license Public domain. */ function bcexp($x, $iters = 7, $scale = 100) { /* Compute e^x. */ $res = bcadd('1.0', $x, $scale); for($i = 0; $i < $iters; $i++) { $res += bcdiv(bcpow($x, bcadd($i, '2'), $scale), bcfact(bcadd($i, '2'), $scale), $scale); } return $res; } /* * Computes ln(x). * @author Thomas Oldbury. * @license Public domain. */ function bcln($a, $iters = 10, $scale = 100) { $result = "0.0"; for($i = 0; $i < $iters; $i++) { $pow = bcadd("1.0", bcmul($i, "2.0", $scale), $scale); //$pow = 1 + ($i * 2); $mul = bcdiv("1.0", $pow, $scale); $fraction = bcmul($mul, bcpow(bcdiv(bcsub($a, "1.0", $scale), bcadd($a, "1.0", $scale), $scale), $pow, $scale), $scale); $result = bcadd($fraction, $result, $scale); } $res = bcmul("2.0", $result, $scale); return $res; } /* * Computes a^b, where a and b can have decimal digits, be negative and/or very large. * Also works for 0^0. Only able to calculate up to 10 digits. Quite slow. * @author Thomas Oldbury. * @license Public domain. */ function bcpowx($a, $b, $iters = 25, $scale = 100) { $ln = bcln($a, $iters, $scale); return bcexp(bcmul($ln, $b, $scale), $iters, $scale); } $precision = 35; echo "3^4.5, precision 15, iters 25 = " . bcpowx('3', '4.5', 25, $precision) . "\n"; echo "4.5^3, precision 15, iters 25 = " . bcpowx('4.5', '3', 25, $precision) . "\n"; echo "8^1/2, precision 15, iters 25 = " . bcpowx('8', '0.5', 25, $precision) . "\n"; echo "28^-1, precision 15, iters 25 = " . bcpowx('28', '-1', 25, $precision) . "\n"; echo "432^0, precision 15, iters 25 = " . bcpowx('432', '0', 25, $precision) . "\n"; echo "0^0, precision 15, iters 25 = " . bcpowx('0.0', '0', 25, $precision) . "\n"; echo "9^999, precision 15, iters 25 = " . bcpowx('9', '999', 25, $precision) . "\n"; echo "9^9999, precision 15, iters 25 = " . bcpowx('9', '9999', 25, $precision) . "\n"; echo "9^99999, precision 15, iters 25 = " . bcpowx('9', '99999', 25, $precision) . "\n"; echo "9^999999, precision 15, iters 25 = " . bcpowx('9', '999999', 25, $precision) . "\n"; echo "9^9999999, precision 15, iters 25 = " . bcpowx('9', '9999999', 25, $precision) . "\n"; echo "9^99999999, precision 15, iters 25 = " . bcpowx('9', '99999999', 25, $precision) . "\n"; echo "9^999999999, precision 15, iters 25 = " . bcpowx('9', '999999999', 25, $precision) . "\n"; echo "9^9999999999, precision 15, iters 25 = " . bcpowx('9', '9999999999', 25, $precision) . "\n"; echo "9^99999999999, precision 15, iters 25 = " . bcpowx('9', '99999999999', 25, $precision) . "\n"; echo "9^999999999999, precision 15, iters 25 = " . bcpowx('9', '999999999999', 25, $precision) . "\n"; ?> ---- Server IP: 92.48.74.199 Probable Submitter: 86.157.97.69 ---- Manual Page -- http://www.php.net/manual/en/ref.bc.php Edit -- https://master.php.net/note/edit/94610 Del: integrated -- https://master.php.net/note/delete/94610/integrated Del: useless -- https://master.php.net/note/delete/94610/useless Del: bad code -- https://master.php.net/note/delete/94610/bad+code Del: spam -- https://master.php.net/note/delete/94610/spam Del: non-english -- https://master.php.net/note/delete/94610/non-english Del: in docs -- https://master.php.net/note/delete/94610/in+docs Del: other reasons-- https://master.php.net/note/delete/94610 Reject -- https://master.php.net/note/reject/94610 Search -- https://master.php.net/manage/user-notes.php