public void checkShape( AbstractMatrix2D B, AbstractMatrix2D C )
 {
     if ( columns != B.columns || rows != B.rows || columns != C.columns || rows != C.rows )
     {
         throw new ArgumentException( "Incompatible Dimensions. " + ToString() + " and " + B.ToString() + " and " + C.ToString() );
     }
 }
 protected abstract String[][] format( AbstractMatrix2D matrix );