Graphics Programs Reference
In-Depth Information
To change the vector
X
from a row vector to a column vector, put a prime (
'
)
after
X
:
>> X'
ans =
0
2
4
6
8
10
Youcanperformmathematicaloperationsonvectors.Forexample,tosquare
the elements of the vector
X
, type
>> X.ˆ2
ans =
0
4
16
36
64
100
The period in this expression is very important; it says that the numbers
in
X
should be squared individually, or
element-by-element
. Typing
Xˆ2
would
tell MATLAB to use matrix multiplication to multiply
X
by itself and would
produce an error message in this case. (We discuss matrices below and in
Chapter 4.) Similarly, you must type
.*
or
./
if you want to multiply or di-
vide vectors element-by-element. For example, to multiply the elements of the
vector
X
by the corresponding elements of the vector
Y
, type
>> X.*Y
ans =
0
-6
20
-12
64
10
Most MATLAB operations are, by default, performed element-by-element.
For example, you do not type a period for addition and subtraction, and you
can type
exp(X)
to get the exponential of each number in
X
(the matrix ex-
ponential function is
expm
). One of the strengths of MATLAB is its ability to
efficiently perform operations on vectors.
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