code: function variance( out, x ) {
  	var len = x.length,
  		i;
  	if ( out.length !== len ) {
  		throw new Error( 'variance()::invalid input arguments. Input and output matrices must be the same length.' );
  	}
  	for ( i = 0; i < len; i++ ) {
  		out.data[ i ] = VARIANCE( x.data[ i ] );
  	}
  	return out;
  }
docs: VARIANCE // 
  FUNCTION: variance( out, x )
  Computes the distribution variance for each parameter stored in a matrix.
  
  @param {Matrix} out - output matrix
  @param {Matrix} x - input matrix
  @returns {Matrix} output matrix