Apart from the
basic operators `+`

, `-`

,
`/`

, `*`

, and `%`

,
PHP provides the usual array of mathematical
library
functions. In this section, we present some of the library functions
that are used with integer and float numbers.

The absolute
value of an integer or a float can be found with the `abs( )`

function:

integer abs(integer number) float abs(float number)

The following examples show the result of `abs( )`

on floats and integers:

echo abs(-1); // prints 1 echo abs(1); // prints 1 echo abs(-145.89); // prints 145.89 echo abs(145.89); // prints 145.89

The `ceil( )`

and `floor( )`

functions can return the integer value above and below a fractional
*value*, respectively:

float ceil(float value) float floor(float value)

The return type is a float because an integer may not be able to represent the result when a large value is passed as an argument. Consider the following examples:

echo ceil(27.3); // prints 28 echo floor(27.3); // prints 27

The `round( )`

function uses 4/5 rounding rules to round up or down a
*value* to a given *precision*:

float round(float value [, integer precision])

Rounding by default is to zero decimal places, but the precision can
be specified with the optional *precision*
argument. The 4/5 rounding rules determine if a number is rounded up
or down based on the digits that are lost due to the rounding
*precision*. For example, 10.4 rounds down to 10, and 10.5 rounds up to 11. The following examples show rounding at ...

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