smarty/docs/en/designers/language-custom-functions/language-function-math.xml

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		<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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