abs  Absolute value
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  Cosine
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  e to the power of ...
expm1  Returns exp(number) - 1, computed in a way that accurate even when the value of number is close to zero 
floor  Round fractions down
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  Base-10 logarithm
log1p  Returns log(1 + number), computed in a way that accurate even when the val ue of number is close to zero 
log  Natural logarithm
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
number_format  Format a number with grouped thousands
octdec  Octal to decimal
pi  Get value of pi
pow  Exponential expression
rad2deg  Converts the radian number to the equivalent number in degrees 
rand  Generate a random value
round  Rounds a float
sin  Sine
sinh  Hyperbolic sine
sqrt  Square root
srand  Seed the random number generator
tan  Tangent
tanh  Hyperbolic tangent