Hi, Testing the examples added by Henrique to help of colnames and rownames functions, I get different outputs for the M matrix: ? matrix M = {1,2;2,1;4,1} matrix M = {1,2;2,1;4,1} Matriz M gerada ? rownames(M, "Row1 Row2 Row3") rownames(M, "Row1 Row2 Row3") ? print M print M M (3 x 2) Row1 1 2 Row2 2 1 Row3 4 1 ? colnames(M, "Col1 Col2") colnames(M, "Col1 Col2") ? print M print M M (3 x 2) Col1 Col2 Row1 1,0000 2,0000 Row2 2,0000 1,0000 Row3 4,0000 1,0000 ? --- This is not a big problem but maybe we should have some control on the matrix elements numeric types (or at least consistency ;)). See ahead that is the colnames setting the numbers to float. In the following experimentation with printf, there are missing separators within the matrix elements (output is using decimal commas since is the PT version): ? matrix M = {1,2;2,1;4,1} matrix M = {1,2;2,1;4,1} Matriz M gerada ? printf "%d", M 12 21 41 ? printf "%0.3g", M 12 21 41 ? printf "%0.3f", M 1,0002,000 2,0001,000 4,0001,000 ? ---- Here I add first the column names: ? colnames(M, "Col1 Col2") colnames(M, "Col1 Col2") ? print M print M M (3 x 2) Col1 Col2 1,0000 2,0000 2,0000 1,0000 4,0000 1,0000 ? rownames(M, "Row1 Row2 Row3") rownames(M, "Row1 Row2 Row3") ? print M print M M (3 x 2) Col1 Col2 Row1 1,0000 2,0000 Row2 2,0000 1,0000 Row3 4,0000 1,0000 ---- ? matrix N = M*1.001 matrix N = M*1.001 Matriz N gerada ? print N print N N (3 x 2) 1,001 2,002 2,002 1,001 4,004 1,001 ? Needs a fix: ? printf "%1.4g", N 1,0012,002 2,0021,001 4,0041,001 ? Note that did not consider the requested 4 decimals. ---- ? rownames(N, "Row1 Row2 Row3") rownames(N, "Row1 Row2 Row3") ? print N print N N (3 x 2) Row1 1,001 2,002 Row2 2,002 1,001 Row3 4,004 1,001 ? colnames(N, "Col1 Col2") colnames(N, "Col1 Col2") ? print N print N N (3 x 2) Col1 Col2 Row1 1,0010 2,0020 Row2 2,0020 1,0010 Row3 4,0040 1,0010 ? It seems that colnames is setting 4 decimals by default :). --- It seems that "%f" is OK: ? printf "%0.04g", N Row1 1,0012,002 Row2 2,0021,001 Row3 4,0041,001 ? printf "%0.04f", N Row1 1,00102,0020 Row2 2,00201,0010 Row3 4,00401,0010 ? printf "%0.05f", N Row1 1,001002,00200 Row2 2,002001,00100 Row3 4,004001,00100 ---- How about the printf when columm names are set? ? printf "%g", N Col1 Col2 Row1 1,0012,002 Row2 2,0021,001 Row3 4,0041,001 ? printf "%d", N Col1Col2 Row1 12 Row2 21 Row3 41 ? --- Summary of fixes : colnames function should leave numeric type untouched (like rownames does) printf should use the same column separation as used by print revise the format "%g" modifier in printf when argument is matrix --- Bye, Hélio