Scripting Guide - SAS

Chapter 7 Data Structures 139
Matrices
Subscripts
Use the subscript operator ([ ]) to pick out elements or submatrices from matrices. The Subscript()
function is usually written as a bracket notation after the matrix to be subscripted, with arguments for rows
and columns.
Single Element
The expression A[i,j] extracts the element in row i, column j, returning a scalar number. The equivalent
functional form is Subscript(A,i,j).
P=[1 2 3, 4 5 6, 7 8 9];
P[2,3]; // returns 6
Subscript(P,2,3); // returns 6
Assign the value that is in the third row and the first column in the matrix A (which is 5) to the variable
test.
A=[1 2, 3 4, 5 6];
test = A[3,1];
Show(test);
test = 5;
Matrix or List Subscripts
To extract a sub-matrix, use matrix or list subscripts. The result is a matrix of the selected rows and columns.
The following expressions select the 2nd and 3rd rows with the 2nd and 1st columns.
P=[1 2 3, 4 5 6, 7 8 9];
P[[2 3],[1 3]]; // matrix subscripts
P[{2,3},{1,3}]; // list subscripts
Both of these methods provide the following output:
[4 6,
7 9]
Single Subscripts
A single subscript addresses matrices as if all the rows were connected end-to-end in a single row. This makes
the double subscript A[i,j] the same as the single subscript A[(i-1)*ncol(A)+j].
Examples
Q = [2 4 6,8 10 12,14 16 18];
Q[8];
16
The following examples all return the column vector [10, 14, 18]:
Q = [2 4 6, 8 10 12, 14 16 18];
Q[{5, 7, 9}];
Q[[5 7 9]];