VECTORS AND M ATRICES
quicksheets
The submatrix function
submatrix(A, ir, jr, ic, jc): Returns the matrix consisting of rows ir th rough jr
and columns ic through jc of array A.
Arguments:
• A, B, C , ... are arrays having the same number of rows for augment, or the same
number of columns for stack.
• ir, jr are the integer upper and lower indices of the rows to be extracted.
• ic, jc are the integer upper and lower indices of the columns to be extracted.
Extracting a Submatrix
This QuickSheet illustrates the use of the submatrix function.
Input matrix: M
1
5−
6−
1
4
7
8−
9−
2
5
1
2−
3−
3
5
4
3
2
4
6
4
3
3
3
8
:=
Extract all elements common to both rows 1 and 2 and columns 0,
1, and 2:
submatrix M 1, 2, 0, 2, ( ) 5−
6−
8−
9−
2−
3−
=
Swapping the last two arguments reverses the order of the columns:
submatrix M 1, 2, 2, 0, ( ) 2−
3−
8−
9−
5−
6−
=
