SPSS® 12.0 Command Syntax Reference

MATRIX—END MATRIX 919
For example, if S is a scalar matrix, S = 2 , R is a row vector, R = 135 , C is a
column vector, C =
2
3
4
, and A is a 5 × 5 matrix, A =
11 12 13 14 15
21 22 23 24 25
31 32 33 34 35
41 42 43 44 45
51 52 53 54 55
, then:
R(S) = R(2) = {3}
C(S) = C(2) = {3}
• An integer index extracts an element from a vector matrix.
• The distinction between a row and a column vector does not matter when an integer index
is used to extract an element from it.
A(2,3) = A(S,3) = {23}
• Two integer indexes separated by a comma extract an element from a rectangular matrix.
A(R,2)=A(1:5:2,2)={12; 32; 52}
A(2,R)=A(2,1:5:2)={21, 23, 25}
A(C,2)=A(2:4,2)= {22;32;42}
A(2,C)=A(2,2:4)= {22,23,24}
• An integer and a vector index separated by a comma extract a vector from a matrix.
• The distinction between a row and a column vector does not matter when used as indexes
in this way.
A(2,:)=A(S,:) = {21, 22, 23, 24, 25}
A(:,2) =A(:,S)= {12; 22; 32; 42; 52}
• A colon by itself used as an index extracts an entire row or column vector from a matrix.
A(R,C)=A(R,2:4)=A(1:5:2,C)=A(1:5:2,2:4)={12,13,14;32,33,34;52,53,54}
A(C,R)=A(C,1:5:2)=A(2:4,R)=A(2:4,1:5:2)={21,23,25;31,33,35;41,43,45}
• Two vector indexes separated by a comma extract a submatrix from a matrix.
• The distinction between a row and a column vector does not matter when used as indexes
in this way.
Construction of a Matrix from Other Matrices
You can use vector or rectangular matrices to construct a new matrix, separating row expressions
by semicolons and components of row expressions by commas. If a column vector Vc has n elements
and matrix M has the dimensions n× m,
then {M, Vc} is an n × ( m + 1)
matrix. Similarly,
if the row vector Vr has m elements and M is the same, then {M; Vr} is an ( n + 1)
×
m
matrix. In fact, you can paste together any number of matrices and vectors this way.