<h3>scale_linear() function</h3>
Transforms a given value from an input domain to an output range using linear interpolation. 

<p><h4>Syntax</h4>
     scale_linear(<i>val</i>,<i>domain_min</i>,<i>domain_max</i>,<i>range_min</i>,<i>range_max</i>)</p>

<p><h4>Arguments</h4>
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<i>  val</i> &rarr; is a value in the input domain. The function will return a corresponding scaled value in the output range.<br>
<i>  domain_min, domain_max</i> &rarr; specify the input domain, the smallest and largest values the input <i>val</i> should take.<br>
<i>  range_min, range_max</i> &rarr; specify the output range, the smallest and largest values which should be output by the function.<br>

<h4>Example</h4>
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     scale_linear(5,0,10,0,100) &rarr; 50<br>
     scale_linear(0.2,0,1,0,360) &rarr; 72 <i>(eg, scaling a value between 0 and 1 to an angle between 0 and 360)</i><br>
     scale_linear(1500,1000,10000,9,20) &rarr; 10.22 <i>(eg, scaling a population which varies between 1000 and 10000 to a font size between 9 and 20)</i><br>