數學常數

常數名	常數值	描述
M_PI	3.14159265358979323846	Pi
M_E	2.7182818284590452354	e
M_LOG2E	1.4426950408889634074	log_2 e
M_LOG10E	0.43429448190325182765	log_10 e
M_LN2	0.69314718055994530942	log_e 2
M_LN10	2.30258509299404568402	log_e 10
M_PI_2	1.57079632679489661923	pi/2
M_PI_4	0.78539816339744830962	pi/4
M_1_PI	0.31830988618379067154	1/pi
M_2_PI	0.63661977236758134308	2/pi
M_SQRTPI	1.77245385090551602729	sqrt(pi) [4.0.2]
M_2_SQRTPI	1.12837916709551257390	2/sqrt(pi)
M_SQRT2	1.41421356237309504880	sqrt(2)
M_SQRT3	1.73205080756887729352	sqrt(3) [4.0.2]
M_SQRT1_2	0.70710678118654752440	1/sqrt(2)
M_LNPI	1.14472988584940017414	log_e(pi) [4.0.2]
M_EULER	0.57721566490153286061	Euler constant [4.0.2]

• acos -- Arc cosine
• acosh -- Inverse hyperbolic cosine
• asin -- Arc sine
• asinh -- Inverse hyperbolic sine
• atan2 -- arc tangent of two variables
• atan -- Arc tangent
• atanh -- Inverse hyperbolic tangent
• base_convert -- Convert a number between arbitrary bases
• bindec -- Binary to decimal
• ceil -- Round fractions up
• cos -- 餘弦
• cosh -- Hyperbolic cosine
• decbin -- Decimal to binary
• dechex -- Decimal to hexadecimal
• decoct -- Decimal to octal
• deg2rad -- Converts the number in degrees to the radian equivalent
• exp -- Calculates the exponent of e (the Neperian or Natural logarithm base)
• expm1 -- Returns exp(number) - 1, computed in a way that is accurate even when the value of number is close to zero
• floor -- Round fractions down
• fmod -- Returns the floating point remainder (modulo) of the division of the arguments
• getrandmax -- Show largest possible random value
• hexdec -- Hexadecimal to decimal
• hypot -- Returns sqrt( num1*num1 + num2*num2)
• is_finite --
• is_infinite --
• is_nan --
• lcg_value -- Combined linear congruential generator
• log10 -- 以10為底的對數
• log1p -- Returns log(1 + number), computed in a way that accurate even when the val ue of number is close to zero
• log -- 自然對數
• max -- Find highest value
• min -- Find lowest value
• mt_getrandmax -- Show largest possible random value
• mt_rand -- Generate a better random value
• mt_srand -- Seed the better random number generator
• octdec -- Octal to decimal
• pi -- 得到圓周率值
• pow -- Exponential expression
• rad2deg -- Converts the radian number to the equivalent number in degrees
• rand -- Generate a random value
• round -- Rounds a float
• sin -- 正弦
• sinh -- Hyperbolic sine
• sqrt -- Square root
• srand -- Seed the random number generator
• tan -- 正切
• tanh -- Hyperbolic tangent

參考