12 Use indexing to select multiple elements from a vector
In MATLAB, a programmer can use a vector of indices to select multiple elements from a vector or array. For example, to get the first and last elements of a vector x
we can write:
x = [9 8 7 6];
ind = [1 numel(x)]; % first and last indices of x
y = x(ind)
Multiple elements of a vector can be changed as well; for example to change the first and last elements of a vector x
we can write:
x = [9 8 7 6];
ind = [1 numel(x)]; % first and last indices of x
x(ind) = [-100 100]
Create a new script and save it as q7.m
.
In the newly created script, add the following:
% v is a vector of random integer values between 1 and 100
% v has between 5 and 10 elements
% everytime this script is run v may have a different
% number of elements and different element values
v = randi(100, [1 randi([5 10], 1)]);
To the script, add some MATLAB statements that perform the following steps in order:
- Gets the first 3 elements of
v
and stores them in a variable namedfirst3
- Gets the last 3 elements of
v
and stores them in a variable namedlast3
- Gets every other element of
v
starting at the first element and stores them in a variable namedeveryOther
- Gets every other element of
v
starting at the second element and stores them in a variable namedeveryOther2