The PHP Online Conference 2021

# Mathematical Functions

• Introduction
• Installing/Configuring
• Predefined Constants
• Math Functions
• 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 — Calculates the exponent of e
• 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 — Calculate the length of the hypotenuse of a right-angle triangle
• intdiv — Integer division
• is_finite — Finds whether a value is a legal finite number
• is_infinite — Finds whether a value is infinite
• is_nan — Finds whether a value is not a number
• lcg_value — Combined linear congruential generator
• log10 — Base-10 logarithm
• log1p — Returns log(1 + number), computed in a way that is accurate even when the value 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 random value via the Mersenne Twister Random Number Generator
• mt_srand — Seeds the Mersenne Twister Random Number Generator
• 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 integer
• round — Rounds a float
• sin — Sine
• sinh — Hyperbolic sine
• sqrt — Square root
• srand — Seed the random number generator
• tan — Tangent
• tanh — Hyperbolic tangent
``` Provides a function to rescale numbers so that the range [a,b] fits into the range [c,d].<?phpfunction rescale(\$ab, \$cd){    list(\$a, \$b) = \$ab;    list(\$c, \$d) = \$cd;    if(\$a == \$b)    {        trigger_error("Invalid scale", E_USER_WARNING);        return false;    }    \$o = (\$b * \$c - \$a * \$d) / (\$b - \$a);    \$s = (\$d - \$c) / (\$b - \$a);    return function(\$x)use(\$o, \$s)    {        return \$s * \$x + \$o;    };}\$fahr2celsius = rescale([32, 212], [0, 100]);echo  \$fahr2celsius(98.6); // 37°C?> ```