100 lines
2.5 KiB
Markdown
100 lines
2.5 KiB
Markdown
# {math}
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`{math}` allows the template designer to do math equations in the
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template.
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## Attributes
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| Attribute Name | Required | Description |
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|----------------|----------|--------------------------------------------------|
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| equation | Yes | The equation to execute |
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| format | No | The format of the result (sprintf) |
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| var | Yes | Equation variable value |
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| assign | No | Template variable the output will be assigned to |
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| \[var \...\] | Yes | Equation variable value |
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- Any numeric template variables may be used in the equations, and the
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result is printed in place of the tag.
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- The variables used in the equation are passed as parameters, which
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can be template variables or static values.
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- +, -, /, \*, abs, ceil, cos, exp, floor, log, log10, max, min, pi,
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pow, rand, round, sin, sqrt, srans and tan are all valid operators.
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Check the PHP documentation for further information on these
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[math](https://www.php.net/eval) functions.
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- If you supply the `assign` attribute, the output of the `{math}`
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function will be assigned to this template variable instead of being
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output to the template.
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> **Note**
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>
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> `{math}` is an expensive function in performance due to its use of the
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> php [`eval()`](https://www.php.net/eval) function. Doing the math in PHP
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> is much more efficient, so whenever possible do the math calculations
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> in the script and [`assign()`](../../programmers/api-functions/api-assign.md) the results to the
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> template. Definitely avoid repetitive `{math}` function calls, eg
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> within [`{section}`](../language-builtin-functions/language-function-section.md) loops.
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## Examples
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**Example 1**
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```smarty
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{* $height=4, $width=5 *}
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{math equation="x + y" x=$height y=$width}
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```
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The above example will output:
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```
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9
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```
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**Example 2**
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```smarty
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{* $row_height = 10, $row_width = 20, #col_div# = 2, assigned in template *}
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{math equation="height * width / division"
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height=$row_height
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width=$row_width
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division=#col_div#}
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```
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The above example will output:
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```
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100
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```
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**Example 3**
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```smarty
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{* you can use parenthesis *}
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{math equation="(( x + y ) / z )" x=2 y=10 z=2}
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```
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The above example will output:
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```
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6
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```
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**Example 4**
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```smarty
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{* you can supply a format parameter in sprintf format *}
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{math equation="x + y" x=4.4444 y=5.0000 format="%.2f"}
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```
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The above example will output:
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```
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9.44
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```
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