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PostgreSQL documentation

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<para>

<xref linkend="functions-math-func-table"> shows the available

mathematical functions. In the table, <literal>dp</literal>

indicates <type>double precision</type>. The functions

<function>exp</function>, <function>ln</function>,

<function>log</function>, <function>pow</function>,

<function>round</function> (1 argument), <function>sqrt</function>,

and <function>trunc</function> (1 argument) are also available for

the type <type>numeric</type> in place of <type>double

precision</type>. Functions returning a <type>numeric</type>

result take <type>numeric</type> input arguments, unless otherwise

specified. Many of these functions are implemented on top of the

host system's C library; accuracy and behavior in boundary cases

could therefore vary depending on the host system.

indicates <type>double precision</type>. Many of these functions

are provided in multiple forms with different argument types.

Except where noted, any given form of a function returns the same

datatype as its argument.

The functions working with <type>double precision</type> data are mostly

implemented on top of the host system's C library; accuracy and behavior in

boundary cases may therefore vary depending on the host system.

</para>

<table id="functions-math-func-table">

</row>

<row>

<entry><function>ceil</function>(<type>numeric</type>)</entry>

<entry><type>numeric</type></entry>

<entry><function>ceil</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>smallest integer not less than argument</entry>

<entry><literal>ceil(-42.8)</literal></entry>

<entry>-42</entry>

</row>

<row>

<entry><function>exp</function>(<type>dp</type>)</entry>

<entry><type>dp</type></entry>

<entry><function>exp</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>exponential</entry>

<entry><literal>exp(1.0)</literal></entry>

<entry>2.71828182845905</entry>

</row>

<row>

<entry><function>floor</function>(<type>numeric</type>)</entry>

<entry><type>numeric</type></entry>

<entry><function>floor</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>largest integer not greater than argument</entry>

<entry><literal>floor(-42.8)</literal></entry>

<entry>-43</entry>

</row>

<row>

<entry><function>ln</function>(<type>dp</type>)</entry>

<entry><type>dp</type></entry>

<entry><function>ln</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>natural logarithm</entry>

<entry><literal>ln(2.0)</literal></entry>

<entry>0.693147180559945</entry>

</row>

<row>

<entry><function>log</function>(<type>dp</type>)</entry>

<entry><type>dp</type></entry>

<entry><function>log</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>base 10 logarithm</entry>

<entry><literal>log(100.0)</literal></entry>

<entry>2</entry>

</row>

<row>

<entry><function>pow</function>(<parameter>e</parameter> <type>dp</type>,

<parameter>n</parameter> <type>dp</type>)</entry>

<entry><function>pow</function>(<parameter>x</parameter> <type>dp</type>,

<parameter>e</parameter> <type>dp</type>)</entry>

<entry><type>dp</type></entry>

<entry>raise a number to exponent <parameter>e</parameter></entry>

<entry><literal>pow(9.0, 3.0)</literal></entry>

<entry>729</entry>

</row>

<row>

<entry><function>pow</function>(<parameter>x</parameter> <type>numeric</type>,

<parameter>e</parameter> <type>numeric</type>)</entry>

<entry><type>numeric</type></entry>

<entry>raise a number to exponent <parameter>e</parameter></entry>

<entry><literal>pow(9.0, 3.0)</literal></entry>

<entry>729</entry>

</row>

<row>

<entry><function>radians</function>(<type>dp</type>)</entry>

<entry><type>dp</type></entry>

<row>

<entry><function>random</function>()</entry>

<entry><type>dp</type></entry>

<entry>value between 0.0to 1.0</entry>

<entry>randomvalue between 0.0and 1.0</entry>

<entry><literal>random()</literal></entry>

<entry></entry>

</row>

<row>

<entry><function>round</function>(<type>dp</type>)</entry>

<entry><type>dp</type></entry>

<entry><function>round</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>round to nearest integer</entry>

<entry><literal>round(42.4)</literal></entry>

<entry>42</entry>

</row>

-->

<row>

<entry><function>sign</function>(<type>numeric</type>)</entry>

<entry><type>numeric</type></entry>

<entry><function>sign</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>sign of the argument (-1, 0, +1)</entry>

<entry><literal>sign(-8.4)</literal></entry>

<entry>-1</entry>

</row>

<row>

<entry><function>sqrt</function>(<type>dp</type>)</entry>

<entry><type>dp</type></entry>

<entry><function>sqrt</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>square root</entry>

<entry><literal>sqrt(2.0)</literal></entry>

<entry>1.4142135623731</entry>

</row>

<row>

<entry><function>trunc</function>(<type>dp</type>)</entry>

<entry><type>dp</type></entry>

<entry><function>trunc</function>(<type>dp</type> or <type>numeric</type>)</entry>

<entry>(same as input)</entry>

<entry>truncate toward zero</entry>

<entry><literal>trunc(42.8)</literal></entry>

<entry>42</entry>

</row>

<row>

<entry><function>trunc</function>(<type>numeric</type>,

<parameter>r</parameter> <type>integer</type>)</entry>

<entry><function>trunc</function>(<parameter>v</parameter> <type>numeric</type>, <parameter>s</parameter> <type>integer</type>)</entry>

<entry><type>numeric</type></entry>

<entry>truncate to <parameter>s</parameter> decimal places</entry>

<entry><literal>trunc(42.4382, 2)</literal></entry>

<para>

Finally, <xref linkend="functions-math-trig-table"> shows the

available trigonometric functions. All trigonometric functions

have arguments and return values of type <type>double

take arguments and return values of type <type>double

precision</type>.

</para>

<para>

This section describes functions and operators for examining and

manipulating binary string values. Strings in this contextinclude

manipulating binary string values. Strings in this contextmean

values of the type <type>BYTEA</type>.

</para>

</row>

<row>

<entry><function>set_byte</function>(<parameter>string</parameter>, <parameter>offset</parameter>)</entry>

<entry><function>set_byte</function>(<parameter>string</parameter>,

<parameter>offset</parameter>, <parameter>newvalue</>)</entry>

<entry><type>bytea</type></entry>

<entry>

Set byte in string.

</row>

<row>

<entry><function>set_bit</function>(<parameter>string</parameter>, <parameter>offset</parameter>)</entry>

<entry><function>set_bit</function>(<parameter>string</parameter>,

<parameter>offset</parameter>, <parameter>newvalue</>)</entry>

<entry><type>bytea</type></entry>

<entry>

Set bit in string.