Location: PHPKode > scripts > RCD Script > rcd-classes/RCD.php
```<?
// Class: RCD
// By: Seb Renauld

class RCD {
function age(\$hlife,\$pca) {
// Returns the age from the half life
// in years, and the percentage of
// activity at the time (where the initial
// activity is 100
//
// For example:
// Carbon 14: half-life: 5568
// pca: 95
if (\$pca <= 100) {
\$alpha = \$hlife/log(2);
\$age = \$alpha*log(100/\$pca);
\$unit = "y";
if (\$age <= 1) {
\$age = \$age*365;
\$unit = "d";
if (\$age <= 1) {
\$age = \$age*24;
\$unit = "h";
if (\$age <= 1) {
// Seconds are more precise :)
\$age = \$age*3600;
\$unit = "s";
}
}
}
return round(\$age,2).\$unit;
}
}
function hlife(\$age,\$curact) {
// Finds the half-life of something
// When the age and current activity is given.
// Reverse of the first formula :)
// Age in years, as ever
if (\$curact <= 100) {
\$alpha = log(100/\$curact)/\$age;
\$hlife = log(2)/\$alpha;
return \$hlife."y";
}
}
function activity(\$age,\$hlife) {
// Finds the current activity (in percent)
// from the age and half-life. Same as ever ;)
\$alpha = \$hlife/log(2);
\$activity = 100 / exp(\$age/\$alpha);
return \$activity."%";
}
}
?>```