diff options
Diffstat (limited to 'src/NextAfter.php')
| -rw-r--r-- | src/NextAfter.php | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/src/NextAfter.php b/src/NextAfter.php index 678de25..d985e6f 100644 --- a/src/NextAfter.php +++ b/src/NextAfter.php @@ -20,6 +20,26 @@ final class NextAfter } /** + * Returns the floating-point number adjacent to $x in the direction of $y. + * If $x equals $y, returns $y. + * + * Special Cases: + * + * - If either argument is NaN, the result is NaN + * - If both arguments equal, $y is returned as it is + * - If $x is minValue() and $y is greater than $x, the result is positive zero + * - If $x is -minValue() and $y is less than $x, the result is negative zero + * - If $x is infinity and $y is not, PHP_FLOAT_MAX is returned + * - If $x is negative infinity and $y is not, -PHP_FLOAT_MAX is returned + * - If $x is PHP_FLOAT_MAX and $y is infinity, infinity is returned + * - If $x is -PHP_FLOAT_MAX and $y is negative infinity, negative infinity is returned + * + * @param float $x + * Starting floating-point number + * @param float $y + * Floating-point number indicating the direction + * @return float + * The floating-point number adjacent to $x in the direction of $y * @phpstan-pure */ public static function nextAfter(float $x, float $y): float @@ -34,6 +54,22 @@ final class NextAfter } /** + * Returns the floating-point number adjacent to $x in the direction of positive infinity. + * + * This is semantically equivalent to nextAfter($x, INF). + * + * Special Cases: + * + * - If $x is NaN, the result is NaN + * - If $x is positive infinity, the result is positive infinity + * - If $x is zero, the result is minValue() + * - If $x is -minValue(), the result is negative zero + * - If $x is PHP_FLOAT_MAX, infinity is returned + * + * @param float $x + * Starting floating-point number + * @return float + * The floating-point number adjacent to $x in the direction of positive infinity * @phpstan-pure */ public static function nextUp(float $x): float @@ -54,6 +90,22 @@ final class NextAfter } /** + * Returns the floating-point number adjacent to $x in the direction of negative infinity. + * + * This is semantically equivalent to nextAfter($x, -INF). + * + * Special Cases: + * + * - If $x is NaN, the result is NaN + * - If $x is negative infinity, the result is negative infinity + * - If $x is zero, the result is -minValue() + * - If $x is minValue(), the result is positive zero + * - If $x is -PHP_FLOAT_MAX, negative infinity is returned + * + * @param float $x + * Starting floating-point number + * @return float + * The floating-point number adjacent to $x in the direction of negative infinity * @phpstan-pure */ public static function nextDown(float $x): float @@ -74,6 +126,13 @@ final class NextAfter } /** + * Returns the minimum representable non-zero floating-point number. + * + * Note that this is a subnormal number and is not the same as PHP_FLOAT_MIN, + * which is the smallest *normal* number. + * + * @return float + * The minimum representable non-zero floating-point number * @phpstan-pure */ public static function minValue(): float |