 Earth's Average Internal Temperature Code
 ```earth->radius_mean_km - 6370 => 7000, \$solSys->earth->radius_mean_km - 5150 => 5000, \$solSys->earth->radius_mean_km - 2900 => 3500, \$solSys->earth->radius_mean_km - 2800 => 3000, \$solSys->earth->radius_mean_km - 200 => 1300, \$solSys->earth->radius_mean_km - 0 => 300, );   // Now we're going to divide the Earth into 100 equal-volume // concentric shells, and we'll assign temperatures to those // volumes, by interpolating between the temps at known radii. \$volumeIncrement = VolumeOfSphere(\$solSys->earth->radius_mean_km) / 100; \$thisVolume = 0; \$temperatures = array(); for (\$i = 1; \$i <= 100; \$i++) { \$thisVolume += \$volumeIncrement; \$thisRadius = RadiusOfSphere(\$thisVolume); \$lastRad = 0; \$lastTmp = 7000; foreach(\$gradientPts as \$rad => \$tmp) { if ((\$thisRadius <= \$rad) and (\$thisRadius >= \$lastRad)) { \$diffRad = \$rad - \$lastRad; \$diffTmp = \$lastTmp - \$tmp; \$diffRadPartial = \$thisRadius - \$lastRad; \$diffTmpPartial = \$lastTmp - (\$diffTmp * (\$diffRadPartial / \$diffRad)); break; } \$lastRad = \$rad; \$lastTmp = \$tmp; } \$temperatures[] = \$diffTmpPartial; }   // Now just average the temperature array, to get // the average temperature inside the Earth. echo (array_sum(\$temperatures) / 100).'
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