Graphics Programs Reference

In-Depth Information

39 Answers to Exercises

(Part I, Basics of MATLAB)

Exercise 1 (Page 9)

The first three columns are a copy of the
a
matrix. The second three

columns are the elements of
a
indexed by the elements of
a
. For example,

a(a(3,2)) = a(8) = 6
, which yields the marked element
>6<
of the

answer:

>> [a a(a)]

ans =

1

2

3

1

4

7

4

5

6

2

5

8

7

8

9

3

>6<

9

Exercise 2 (Page 39)

function out = posneg(in)

% Test for all positive (1), or all negative (-1) elements.

if all(in>0)

out=1;

elseif all(in<0)

out = -1;

else

out=0;

end

Exercise 3 (Page 44)

The clown's hair is orange. You can use
load clown
to load the data

(type
clear
first to get rid of any superfluous data). Typing
whos
will

tell you that the workspace contains a matrix
X
and a variable
map
. Use

image(X),colormap(map)
to view the image.

Exercise 4 (Page 49)

We want to fit the data to an exponential curve:

p
=
Ae
Bx
.

First we take logs to convert to a linear equation:

log
p
= log
A
+
Bx.