Page 25 - MATLAB an introduction with applications

10 ——— MATLAB: An Introduction with Applications

1.9.4 Addressing Arrays
A colon can be used in MATLAB to address a range of elements in a vector or a matrix.

1.9.4.1 Colon for a vector
Va(:) – refers to all the elements of the vector Va (either a row or a column vector).
Va(m:n) – refers to elements m through n of the vector Va.
For instance,
>> V = [2 5 –1 11 8 4 7 –3 11]
>> u = V (2 :8)
u = 5 –1 11 8 4 7 –3 11

1.9.4.2 Colon for a matrix
Table 1.16 gives the use of a colon in addressing arrays in a matrix.
Table 1.16 Colon use for a matrix
Command Description
A(:, n) Refers to the elements in all the rows of a column n of the matrix A.
A(n, :) Refers to the elements in all the columns of row n of the matrix A.
A(:, m:n) Refers to the elements in all the rows between columns m and n of
the matrix A.
A(m:n, :) Refers to the elements in all the columns between rows m and n of
the matrix A.
A(m:n, p:q) Refers to the elements in rows m through n and columns p through
q of the matrix A.

1.9.5 Adding Elements to a Vector or a Matrix
A variable that exists as a vector or a matrix can be changed by adding elements to it. Addition of elements is
done by assigning values of the additional elements, or by appending existing variables. Rows and/or columns
can be added to an existing matrix by assigning values to the new rows or columns.

1.9.6 Deleting Elements
An element or a range of elements of an existing variable can be deleted by reassigning blanks to these
elements. This is done simply by the use of square brackets with nothing typed in between them.

1.9.7 Built-in Functions
Some of the built-in functions available in MATLAB for managing and handling arrays as listed in
Table 1.17.

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