Mathematical Functions

Introduction

These math functions will only handle values within the range of the long and double types on your computer. If you need to handle bigger numbers, take a look at the arbitrary precision math functions.

Math constants

The following values are defined as constants in PHP by the math extension:

Table 1. Math constants

Mathematical Functions

Abs

Acos

Asin

Name

Abs — absolute value

Description

mixed abs(mixed number);

Returns the absolute value of number. If the argument number is float, return type is also float, otherwise it is int.

Name

Acos — arc cosine

Description

float acos(float arg);

Returns the arc cosine of arg in radians. See also asin and atan.

Name

Asin — arc sine

Description

float asin(float arg);

Returns the arc sine of arg in radians. See also acos and atan.

Atan

Atan2

Name

Atan — arc tangent

Description

float atan(float arg);

Returns the arc tangent of arg in radians. See also acos and atan.

Name

Atan2 — arc tangent of two variables

Description

float atan2(float y, float x);

This function calculates the arc tangent of the two variables x and y. It is similar to calculating the arc tangent of y / x, except that the signs of both arguments are used to determine the quadrant of the result.

The function returns the result in radians, which is between -PI and PI (inclusive). See also acos and atan.

base_convert

Name

base_convert — convert a number between arbitrary bases

Description

strin base_convert(string number, int frombase, int tobase);

Returns a string containing number represented in base tobase. The base in which number is given is specified in frombase. Both frombase and tobase have to be between 2 and 36, inclusive.

Digits in numbers with a base higher than 10 will be represented with the letters a-z, with a meaning 10, b meaning 11 and z meaning 36.

Example 1. base_convert()

$binary = base_convert($hexadecimal, 16, 2);

BinDec

Name

BinDec — binary to decimal

Description

int bindec(string binary_string);

Ceil

Cos

Returns the decimal equivalent of the binary number represented by the binary_string argument.

OctDec converts a binary number to a decimal number. The largest number that can be converted is 31 bits of 1's or 2147483647 in decimal.

See also the decbin function.

Name

Ceil — round fractions up

Description

int ceil(float number);

Returns the next highest integer value from number. Using ceil on integers is absolutely a waste of time.

NOTE: PHP/FI 2's ceil returned a float. Use: $new = (double)ceil($number); to get the old behaviour.

See also floor and round.

Name

Cos — cosine

Description

float cos(float arg);

Returns the cosine of arg in radians. See also sin and tan.

DecBin

Name

DecBin — decimal to binary

Description

string decbin(int number);

Returns a string containing a binary representation of the given number argument. The largest number that can be converted is 2147483647 in decimal resulting to a string of 31 1's.

See also the bindec function.

DecHex

Name

DecHex — decimal to hexadecimal

Description

string dechex(int number);

Returns a string containing a hexadecimal representation of the given number argument. The largest number that can be converted is 2147483647 in decimal resulting to "7fffffff".

See also the hexdec function.

DecOct

Name

DecOct — decimal to octal

Description

string decoct(int number);

Returns a string containing an octal representation of the given number argument. The largest number that can be converted is 2147483647 in decimal resulting to "17777777777". See also octdec.

Exp

Floor

Name

Exp — e to the power of...

Description

float exp(float arg);

Returns e raised to the power of arg. See also pow.

Name

Floor — round fractions down

Description

int floor(float number);

Returns the next lowest integer value from number. Using floor on integers is absolutely a waste of time.

NOTE: PHP/FI 2's floor returned a float. Use: $new = (double)floor($number); to get the old behaviour.

See also ceil and round.

getrandmax

Name

getrandmax — show largest possible random value

Description

int getrandmax(void );

Returns the maximum value that can be returned by a call to rand. See also rand and srand.

HexDec

Name

HexDec — hexadecimal to decimal

Description

int hexdec(string hex_string);

Log

Returns the decimal equivalent of the hexadecimal number represented by the hex_string argument. HexDec converts a hexadecimal string to a decimal number. The largest number that can be converted is 7fffffff or 2147483647 in decimal.

See also the dechex function.

Name

Log — natural logarithm

Description

float log(float arg);

Returns the natural logarithm of arg.

Log10

Name

Log10 — base-10 logarithm

Description

float log10(float arg);

Returns the base-10 logarithm of arg.

max

min

Name

max — find highest value

Description

mixed max(mixed arg1, mixed arg2, mixed argn); max returns the numerically highest of the parameter values.

If the first parameter is an array, max returns the highest value in that array. If the first parameter is an integer, string or double, you need at least two parameters and max returns the biggest of these values. You can compare an unlimited number of values.

If one or more of the values is a double, all the values will be treated as doubles, and a double is returned. If none of the values is a double, all of them will be treated as integers, and an integer is returned.

Name

min — find lowest value

Description

mixed min(mixed arg1, mixed arg2, mixed argn); min returns the numerically lowest of the parameter values.

If the first parameter is an array, min returns the lowest value in that array. If the first parameter is an integer, string or double, you need at least two parameters and min returns the lowest of these values. You can compare an unlimited number of values.

If one or more of the values is a double, all the values will be treated as doubles, and a double is returned. If none of the values is a double, all of them will be treated as integers, and an integer is returned.

number_format

Name

number_format — format a number with grouped thousands

Description

string number_format(float number, int decimals, string dec_point, string

thousands_sep);

number_format returns a formatted version of number. This function accepts either one, two or four parameters (not three):

If only one parameter is given, number will be formatted without decimals, but with a comma (",") between every group of thousands.

If two parameters are given, number will be formatted with decimals decimals with a dot (".") in front, and a comma (",") between every group of thousands.

If all four parameters are given, number will be formatted with decimals decimals, dec_point instead of a dot (".") before the decimals and thousands_sep instead of a comma (",") between every group of thousands.

OctDec

Name

OctDec — octal to decimal

Description

int octdec(string octal_string);

Returns the decimal equivalent of the octal number represented by the octal_string argument. OctDec converts an octal string to a decimal number. The largest number that can be converted is 17777777777 or 2147483647 in decimal.

See also decoct.

pi

pow

rand

Name

pi — get value of pi

Description

double pi(void );

Returns an approximation of pi.

Name

pow — exponential expression

Description

float pow(float base, float exp);

Returns base raised to the power of exp. See also exp.

Name

rand — generate a random value

Description

int rand([int min], [int max]);

If called without the optional min,max arguments rand() returns a pseudo-random value between 0 and RAND_MAX. If you want a random number between 5 and 15 (inclusive), for example, use rand(5,15).

Remember to seed the random number generator before use with srand.

round

Name

round — Rounds a float.

Description

double round(double val);

Returns the rounded value of val.

$foo = round( 3.4 ); // $foo == 3.0

$foo = round( 3.5 ); // $foo == 4.0

$foo = round( 3.6 ); // $foo == 4.0

Sin

Sqrt

See also ceil and floor.

Name

Sin — sine

Description

float sin(float arg);

Returns the sine of arg in radians. See also cos and tan.

Name

Sqrt — square root

Description

float sqrt(float arg);

Returns the square root of arg.

srand

Tan

Name

srand — seed the random number generator

Description

void srand(int seed);

Seeds the random number generator with seed.

// seed with microseconds since last "whole" second srand((double)microtime()*1000000);

$randval = rand();

See also rand and getrandmax.

Name

Tan — tangent

Description

float tan(float arg);

Returns the tangent of arg in radians. See also sin and cos.