HP 39g+ - Manual (Page 185)

Matrices 12-13
TRACE Finds the trace of a square matrix. The trace is equal to the
sum of the diagonal elements. (It is also equal to the sum of
the eigenvalues.)
TRACE(matrix)
TRN Transposes matrix. For a complex matrix, TRN finds the
conjugate transpose.
TRN(matrix)
Examples
Identity Matrix You can create an identity matrix with the IDENMAT
function. For example, IDENMAT(2) creates the 2×2 identity
matrix [[1,0],[0,1]].
You can also create an identity matrix using the MAKEMAT
(make matrix) function. For example, entering
MAKEMAT(I
≠
J,4,4) creates a 4 × 4 matrix showing the
numeral 1 for all elements except zeros on the diagonal. The
logical operator
≠
returns 0 when I (the row number) and J
(the column number) are equal, and returns 1 when they are
not equal.
Transposing a
Matrix The TRN function swaps the row-column and column-row
elements of a matrix. For instance, element 1,2 (row 1,
column 2) is swapped with element 2,1; element 2,3 is
swapped with element 3,2; and so on.
For example, TRN([[1,2],[3,4]]) creates the matrix
[[1,3],[2,4]].