question: public static TetradMatrix convertCovToCorr ( TetradMatrix m ) { for ( int i = 0 ; i < m . rows ( ) ; i ++ ) { for ( int j = 0 ; j < m . columns ( ) ; j ++ ) { if ( Double . isNaN ( m . get ( i , j ) ) ) { throw new IllegalArgumentException ( "Please remove or impute missing values." ) ; } } } return correlation ( m ) ; }
target:  Converts a covariance matrix to a correlation matrix in place; the same matrix is returned for convenience, but m is modified in the process.