Question

Using Matlab please answer problem 1, parts a and b. Please explain each for part a. Please explain the result for part b.

1. MATLAB ARRAY INDEXING

(a) Explain what the each of the following will produce:

jk1 = 2:4:17

      jk1 = 99:-1:88

ttt = 2:(1/9):4

(b) Extract or insert numbers in a vector. Try the following:

xx= [ ones(1,4), [2:2:11], zeros(1,3) ]

xx(3:7)

length(xx)

Explain the result.

Answer 1

jk1 = 2:4:17 creates a vector starting from 2 ending with 17 with step size 4

2    6   10   14

jk1 = 99:-1:88 creates a vector staring from 99 upto 88 by decrementing 1 each time

99   98   97   96   95   94   93   92   91   90   89   88

ttt = 2:(1/9):4 creates a vector from 2 to 4 with step size 1/9
ttt =

 Columns 1 through 8:

    2.0000    2.1111    2.2222    2.3333    2.4444    2.5556    2.6667    2.7778

 Columns 9 through 16:

    2.8889    3.0000    3.1111    3.2222    3.3333    3.4444    3.5556    3.6667

 Columns 17 through 19:

    3.7778    3.8889    4.0000

b)

ones(1,4) gives 1 row 4 columns 1s -> 1 1 1 1

[2 2 11] gives 2 4 6 8 10

zeros(1,3) zeros of 1 row and 3 columns -> 0 0 0

appending all these gives xx = [1 1 1 1 2 4 6 8 10 0 0 0]

xx(3:7) gives a vector of elements xx starting from 3 to 7 --> 1 1 2 4 6

length(xx) gives length of xx that is 12