In this book, we use the following convention for 2D arrays: “row” refers to the first index of the array and “column” refers to the second. So for a 2D array A, A(i,j) is the element in row i and column j. The PM command makes this easy to visualize:

a = INTARR( 4, 8 )    &    a(2,5) = 1    &    PM, a

0   0   0   0   0   0   0   0

0   0   0   0   0   0   0   0

0   0   0   0   0   1   0   0

0   0   0   0   0   0   0   0