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Predefined Constants
The constants below are always available as part of the PHP core.
Mathematical Constants
-
M_PI
(float)
-
Approximation of the number π (pi).
(
3.14159265358979323846).
-
M_E
(float)
-
Approximation of Euler's number
e
(2.7182818284590452354).
-
M_LOG2E
(float)
-
Approximation of
log2(e)
(1.4426950408889634074).
-
M_LOG10E
(float)
-
Approximation of
log10(e)
(0.43429448190325182765).
-
M_LN2
(float)
-
Approximation of
ln(2)
(0.69314718055994530942).
-
M_LN10
(float)
-
Approximation of
ln(10)
(2.30258509299404568402).
-
M_PI_2
(float)
-
Approximation of
π/2
(1.57079632679489661923).
-
M_PI_4
(float)
-
Approximation of
π/4
(0.78539816339744830962).
-
M_1_PI
(float)
-
Approximation of
1/π
(0.31830988618379067154).
-
M_2_PI
(float)
-
Approximation of
2/π
(0.63661977236758134308).
-
M_SQRTPI
(float)
-
Approximation of
sqrt(π)
(1.77245385090551602729).
-
M_2_SQRTPI
(float)
-
Approximation of
2/sqrt(π)
(1.12837916709551257390).
-
M_SQRT2
(float)
-
Approximation of
sqrt(2)
(1.41421356237309504880).
-
M_SQRT3
(float)
-
Approximation of
sqrt(3)
(1.73205080756887729352).
-
M_SQRT1_2
(float)
-
Approximation of
1/sqrt(2)
(0.70710678118654752440).
-
M_LNPI
(float)
-
Approximation of
ln(π)
(1.14472988584940017414).
-
M_EULER
(float)
-
Approximation of Euler's constant γ
(
0.57721566490153286061).
IEEE 754 floating point constants
-
NAN
(float)
-
Not A Number
-
INF
(float)
-
Infinity
Rounding constants
Note:
As of PHP 8.4.0, it is recommended to use the
RoundingMode
enum instead.
-
PHP_ROUND_HALF_UP
(int)
-
Rounding half away from zero.
-
PHP_ROUND_HALF_DOWN
(int)
-
Rounding half toward zero.
-
PHP_ROUND_HALF_EVEN
(int)
-
Round halves to even numbers
-
PHP_ROUND_HALF_ODD
(int)
-
Round halves to odd numbers
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