HP 50g Graphing Calculator - Manual (Page 325)

Page 10-24
Function ROW-
Function ROW- takes as argument a matrix and an integer number representing
the position of a row in the matrix. The function returns the original matrix,
minus a row, as well as the extracted row shown as a vector. Here is an
example in the ALG mode using the matrix stored in A:
In RPN mode, place the matrix in the stack first, then enter the number
representing a row location before applying function ROW-. The following
figure shows the RPN stack before and after applying function ROW-.
Function RSWP
Function RSWP (Row SWaP) takes as arguments two indices, say, i and j,
(representing two distinct rows in a matrix), and a matrix, and produces a new
matrix with rows i and j swapped. The following example, in ALG mode,
shows an application of this function. We use the matrix stored in variable A
for the example. This matrix is listed first.
In RPN mode, function RSWP lets you swap the rows of a matrix listed in stack
level 3, whose indices are listed in stack levels 1 and 2. For example, the
following figure shows the RPN stack before and after applying function RSWP
to matrix A in order to swap rows 2 and 3: