public static Number::validStep($value, $step, $offset = 0.0)
Verifies that a number is a multiple of a given step.
The implementation assumes it is dealing with IEEE 754 double precision floating point numbers that are used by PHP on most systems.
This is based on the number/range verification methods of webkit.
Parameters
float $value: The value that needs to be checked.
float $step: The step scale factor. Must be positive.
float $offset: (optional) An offset, to which the difference must be a multiple of the given step.
Return value
bool TRUE if no step mismatch has occurred, or FALSE otherwise.
See also
http://opensource.apple.com/source/WebCore/WebCore-1298/html/NumberInput...
File
- core/lib/Drupal/Component/Utility/Number.php, line 33
Class
- Number
- Provides helper methods for manipulating numbers.
Namespace
Drupal\Component\Utility
Code
public static function validStep($value, $step, $offset = 0.0) { $double_value = (double) abs($value - $offset); // The fractional part of a double has 53 bits. The greatest number that // could be represented with that is 2^53. If the given value is even bigger // than $step * 2^53, then dividing by $step will result in a very small // remainder. Since that remainder can't even be represented with a single // precision float the following computation of the remainder makes no sense // and we can safely ignore it instead. if ($double_value / pow(2.0, 53) > $step) { return TRUE; } // Now compute that remainder of a division by $step. $remainder = (double) abs($double_value - $step * round($double_value / $step)); // $remainder is a double precision floating point number. Remainders that // can't be represented with single precision floats are acceptable. The // fractional part of a float has 24 bits. That means remainders smaller than // $step * 2^-24 are acceptable. $computed_acceptable_error = (double) ($step / pow(2.0, 24)); return $computed_acceptable_error >= $remainder || $remainder >= ($step - $computed_acceptable_error); }
Please login to continue.