Map value to color scale

Map_value_to_color_scale.php

<!-- Map value to color scale -->
<?php
function lineargradient($ra,$ga,$ba,$rz,$gz,$bz,$iterationnr) {
    $colorindex = array();
    for($iterationc=1; $iterationc<=$iterationnr; $iterationc++) {
       $iterationdiff = $iterationnr-$iterationc;
       $colorindex[] = '#'.
          dechex(intval((($ra*$iterationc)+($rz*$iterationdiff))/$iterationnr)).
          dechex(intval((($ga*$iterationc)+($gz*$iterationdiff))/$iterationnr)).
          dechex(intval((($ba*$iterationc)+($bz*$iterationdiff))/$iterationnr));
    }
    return $colorindex;
}

$colorindex = lineargradient(
    100, 0, 0,   // rgb of the start color
    0, 255, 255, // rgb of the end color
    100          // number of colors in your linear gradient
);

$color = $colorindex[1];
?>