PHP math functions: mean(), median(), variance(), covariance(), correlation(), stddev(), pv(), npv(), and more.

#Functions

##mean(array $values)

Parameters:

• Array $values - Array of numeric values.

Returns: String Arithmetic average of the given values.

Alias: avg()

##median(array $values)

Parameters:

• Array $values - Array of numeric values

Returns: String Median value of the given values, or null if it cannot be computed.

##sumxy(array $x_values, array $y_values)

Parameters:

• Array $x_values - Array of numeric values of x.
• Array $y_values - Array of numeric values of y.

Returns: String Sum of the products of the values.

##sos(array $values, $values2 = null)

Parameters:

• Array $values - Array of numeric values.
• Null|Array|String $values2 - Optional - If null, simply sums the square of each array value. If given a scalar value, sums the squares of the difference between each array value and that given by $values2 (good for explained/regression SS). If given an array, sums the squares of the difference between betweeen each array value and the value in $values2 with matching key (good for residual SS).

Returns: String Sum of squares.

##variance(array $values, $is_sample = false)

Returns: String Variance

##stddev(array $a, $is_sample = false)

Returns: String Standard deviation

Alias: stdev()

##covariance(array $x_values, array $y_values)

Returns: String Covariance

Alias: covar()

##correlation(array $x_values, array $y_values)

Returns: String Correlation

Alias: correl()

##pv($cashflow, $rate, $period = 0)

Returns: String Present value

##npv(array $cashflows, $rate)

Returns: String Net present value

##weighted_avg(array $values, array $weights)

Returns: String Weighted average

##pct($portion, $total)

Returns: String Percent

##pct_change($current, $previous)

Returns: String Percent change

##pct_change_array(array $values)

Returns: Array Array values percent change