Let me see if I can clarify:
If you pass a _string_ such as "1E2" to a BC math function, it will stop reading as soon as it sees the "E". (The BC math functions do not know scientific notation.)
If you set the variable $foo equal to the _numeric_ 1E2, the variable $foo will then contain the mathematical number known as "one hundred".
If you then pass $foo to a BC math function, PHP will convert the contents of $foo (the mathematical number one hundred) into the string "100". This is the same exact behaviour you would get if you tried to evaluate $foo." apples": you have something which expects a string but you are passing it a number, so the number gets converted to a string.
However, if you try to pass a googol (or rather, the closest IEEE double-precision floating-point number to a googol) to BC math this way, I would not expect it to work. Why? Because PHP would try to write that googol (excuse me, approximation to a googol) in scientific notation (it would, wouldn't it? I'm too lazy to try it), and BC math does not know scientific notation. So there.
bcdiv
Description
string bcdiv ( string left_operand, string right_operand [, int scale] )Divides the left_operand by the right_operand and returns the result. The optional scale sets the number of digits after the decimal place in the result, which defaults to 0.
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User Contributed Notes
Robert Lozyniak
06-May-2006 07:05
06-May-2006 07:05
artmine77 at yahoo dot com
10-Oct-2005 01:47
10-Oct-2005 01:47
Block 1:
{
$arg1="1E+11";
$arg2="5";
$ret=bcdiv($arg1,$arg2,0); // $ret=0 (calculation error)
}
Block 2:
{
$arg1=1E+11;
$arg2=5;
$ret=bcdiv($arg1,$arg2,0); // $ret=20000000000
}
Why do the manual says that $arg1 and $arg2 should be strings when that's when the error happens? If someone knows, I would appreciate the answer.
cristianDOTzuddas]NOSPAM[gmailDOTcom
24-Jul-2005 08:10
24-Jul-2005 08:10
Decimal to binary conversion, using BC Math.
Note: this function is VERY slow if the decimal number is too big!
<?
function bc_decbin($dec_str) {
if (strlen($dec_str)>0) {
$bin_str = '';
do {
if (((int)$dec_str[strlen($dec_str)-1] % 2) === 0)
$bin_str .= '0';
else
$bin_str .= '1';
$dec_str = bcdiv($dec_str, '2');
} while ($dec_str!='0');
return strrev($bin_str);
}
else
return null;
}
?>
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Cristian
www.CodeFlower.com