find the variance of all values in a map in php

To find the variance of all values in a map in PHP, first, we need to calculate the mean of the values. Then, we will subtract the mean from each value and square the result. Finally, we will get the average of the squared differences to get the variance.

Here's the PHP code to perform this calculation:

main.php
<?php
$values = array(5, 6, 7, 8, 9);
$mean = array_sum($values) / count($values);
$variance = 0.0;
foreach($values as $value) {
  $variance += pow($value - $mean, 2);
}
$variance /= count($values);

echo $variance; // Output: 2.0
?>
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In this example, we have an array of values and we calculate the mean using the array_sum function and dividing by the number of values using count. Then, we loop through each value, subtract the mean, and square the result using the pow function. Finally, we add up all the squared differences and divide by the number of values to get the variance. The result is output using echo.