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smarty/docs/en/designers/language-custom-functions/language-function-math.xml
2004-04-13 08:46:28 +00:00

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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision$ -->
<sect1 id="language.function.math">
<title>math</title>
<informaltable frame="all">
<tgroup cols="5">
<colspec colname="param" align="center" />
<colspec colname="type" align="center" />
<colspec colname="required" align="center" />
<colspec colname="default" align="center" />
<colspec colname="desc" />
<thead>
<row>
<entry>Attribute Name</entry>
<entry>Type</entry>
<entry>Required</entry>
<entry>Default</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry>equation</entry>
<entry>string</entry>
<entry>Yes</entry>
<entry><emphasis>n/a</emphasis></entry>
<entry>the equation to execute</entry>
</row>
<row>
<entry>format</entry>
<entry>string</entry>
<entry>No</entry>
<entry><emphasis>n/a</emphasis></entry>
<entry>the format of the result (sprintf)</entry>
</row>
<row>
<entry>var</entry>
<entry>numeric</entry>
<entry>Yes</entry>
<entry><emphasis>n/a</emphasis></entry>
<entry>equation variable value</entry>
</row>
<row>
<entry>assign</entry>
<entry>string</entry>
<entry>No</entry>
<entry><emphasis>n/a</emphasis></entry>
<entry>template variable the output will be assigned to</entry>
</row>
<row>
<entry>[var ...]</entry>
<entry>numeric</entry>
<entry>Yes</entry>
<entry><emphasis>n/a</emphasis></entry>
<entry>equation variable value</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>
math allows the template designer to do math equations in the
template. Any numeric template variables may be used in the
equations, and the result is printed in place of the tag. The
variables used in the equation are passed as parameters, which can
be template variables or static values. +, -, /, *, abs, ceil, cos,
exp, floor, log, log10, max, min, pi, pow, rand, round, sin, sqrt,
srans and tan are all valid operators. Check the PHP documentation
for further information on these math functions.
</para>
<para>
If you supply the special "assign" attribute, the output of the
math function will be assigned to this template variable instead of
being output to the template.
</para>
<note>
<title>Technical Note</title>
<para>
math is an expensive function in performance due to its use of
the php eval() function. Doing the math in PHP is much more
efficient, so whenever possible do the math calculations in PHP
and assign the results to the template. Definately avoid
repetitive math function calls, like within section loops.
</para>
</note>
<example>
<title>math</title>
<programlisting>
{* $height=4, $width=5 *}
{math equation="x + y" x=$height y=$width}
OUTPUT:
9
{* $row_height = 10, $row_width = 20, #col_div# = 2, assigned in template *}
{math equation="height * width / division"
height=$row_height
width=$row_width
division=#col_div#}
OUTPUT:
100
{* you can use parenthesis *}
{math equation="(( x + y ) / z )" x=2 y=10 z=2}
OUTPUT:
6
{* you can supply a format parameter in sprintf format *}
{math equation="x + y" x=4.4444 y=5.0000 format="%.2f"}
OUTPUT:
9.44</programlisting>
</example>
</sect1>
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