Question

given a row vector x create each of the following row vectors as indicated

y is two copies of x, one after another (a vector twice as large as x, containing two copies)

z is a vector containing the elements of x with odd indices

w is identical to x, except it contains the number 0 inserted before the first element of x, a 7 inserted after the fourth element of x, and 12 inserted after the last element of x(thus, w is 3 elements larger than x)

how would i find the vecotors for these

x = randi([-9,9],1,8)

Answer 1

It is inferred from the last line of question that this is asked in MATLAB

For making a new vector with two copies Use the following command

y=[x x]

we write our new elements inside [] to create a new vector.

For elements of x with odd indices use

z=x(1:2:end)

(for even do this x(2:2:end) )

Understand this notation x(a:b:c) this will return vector with elements of x indices from a to c with the step of b. Means if b=2 we will get every 2nd element if b=3 we will get every third element. If we don't specify anything like x(a:c) it will be like b=1 and will return all elements from indices a to c. end is used to specify to go till the last element.

w=[0 x(1:4) 7 x(5:end) 12]

A similar concept that was used to create y and z is used to create w. First, we started with element 0 and then added element of x from 1 to 4 than inserted 7. than added all remaining element of x using x(5:end) and finally 12 at the end.

MATLAB code:

x = randi([-9,9],1,8)
y=[x x]
z=x(1:2:end)
w=[0 x(1:4) 7 x(5:end) 12]