PAREN

( ) Parentheses are used to indicate precedence in arithmetic

expressions and to enclose arguments of functions in the

usual way. They are used to enclose subscripts of vectors

and matrices in a manner somewhat more general than the

usual way. If X and V are vectors, then X(V) is

[X(V(1)), X(V(2)), ..., X(V(N))]. The components of V

are rounded to nearest integers and used as subscripts. An

error occurs if any such subscript is less than 1 or

greater than the dimension of X. Some examples:

X(3) is the third element of X.

X([1 2 3]) is the first three elements of X. So is

X([SQRT(2), SQRT(3), 4*ATAN(1)]).

If X has N components, X(N:-1:1) reverses them.

The same indirect subscripting is used in matrices. If V

has M components and W has N components, then A(V,W)

is the M-by-N matrix formed from the elements of A whose

subscripts are the elements of V and W. For example...

A([1,5],:) = A([5,1],:) interchanges rows 1 and 5 of A.

[ ] Brackets are used in forming vectors and matrices.

[6.9 9.64 SQRT(-1)] is a vector with three elements

separated by blanks. [6.9, 9.64, sqrt(-1)] is the same

thing. [1+I 2-I 3] and [1 +I 2 -I 3] are not the same.

The first has three elements, the second has five.

[11 12 13; 21 22 23] is a 2-by-3 matrix. The semicolon

ends the first row.

Vectors and matrices can be concatenated with [ ] brackets.

[A B; C] is allowed if the number of rows of A equals

the number of rows of B and the number of columns of A

plus the number of columns of B equals the number of

columns of C. This rule generalizes in a hopefully

obvious way to allow fairly complicated constructions.

A = [ ] stores an empty matrix in A. See CLEAR to remove

variables from the current workspace.

For the use of [ and ] on the left of the = in multiple

assignment statements, see LU, EIG, SVD and so on.

Copyright (c) 1984-93 by The MathWorks, Inc.