Finding the maximum value in a matrix

[Memetteoman]

I am working with firm-level panel data with a firm identifier (ident) and a year variable (year). For the same firm (here ident=102) and for different years (year=2010-2013), I have values on four variables (X1-X4). I would like to write a code that generates for each firm (here ident=102) and for all the years a new variable that contains the maximum (non-missing) value in the matrix, that is 5. I used the code egen new=rowmax(X1-X4) but it didn't work. Any suggestion is welcome.

ident	year	X1	X2	X3	X4
102	2010	2	3	4	5
102	2011	2	3	4	.
102	2012	2	3	.	.
102	2013	2	.	.	.

[Daniel Schaefer]

clear
input int(ident    year    X1    X2    X3    X4)
102    2010    2    3    4    5
102    2011    2    3    4    .
102    2012    2    3    .    .
102    2013    2    .    .    .
103    2010    2    3    4    5
103    2011    2    6    4    .
103    2012    2    3    .    .
103    2013    2    .    .    .
end

egen rowmax = rowmax(X1-X4)
bysort ident: egen wanted = max(rowmax)
list, clean noobs

. list, clean noobs

    ident   year   X1   X2   X3   X4   rowmax   wanted  
      102   2010    2    3    4    5        5        5  
      102   2011    2    3    4    .        4        5  
      102   2012    2    3    .    .        3        5  
      102   2013    2    .    .    .        2        5  
      103   2010    2    3    4    5        5        6  
      103   2011    2    6    4    .        6        6  
      103   2012    2    3    .    .        3        6  
      103   2013    2    .    .    .        2        6

[Memetteoman]

Dear Daniel, thank you for the solution.