# Statistics

I hope that someday Octave will include more statistics functions. If you would like to help improve Octave in this area, please contact `bug-octave@che.utexas.edu`.

`corrcoef (x [, y])`
If each row of x and y is an observation and each column is a variable, the (i,j)-th entry of `corrcoef (x, y)` is the correlation between the i-th variable in x and the j-th variable in y. If invoked with one argument, compute `corrcoef (x, x)`.
`cov (x [, y])`
If each row of x and y is an observation and each column is a variable, the (i,j)-th entry of `cov (x, y)` is the covariance between the i-th variable in X and the j-th variable in y. If invoked with one argument, compute `cov (x, x)`.
`kurtosis (x)`
If x is a vector of length N, return the kurtosis
```kurtosis(x) = N^(-1) std(x)^(-4) SUM_i (x(i)-mean(x))^4 - 3
```
of x. If x is a matrix, return the row vector containing the kurtosis of each column.
`mahalanobis (x, y)`
Returns Mahalanobis' D-square distance between the multivariate samples x and y, which must have the same number of components (columns), but may have a different number of observations (rows).
`mean (a)`
If a is a vector, compute the mean of the elements of a. If a is a matrix, compute the mean for each column and return them in a row vector.
`median (a)`
If a is a vector, compute the median value of the elements of a. If a is a matrix, compute the median value for each column and return them in a row vector.
`skewness (x)`
If x is a vector of length N, return the skewness
```skewness (x) = N^(-1) std(x)^(-3) SUM_i (x(i)-mean(x))^3
```
of x. If x is a matrix, return the row vector containing the skewness of each column.
`std (a)`
If a is a vector, compute the standard deviation of the elements of a. If a is a matrix, compute the standard deviation for each column and return them in a row vector.