Graphics Programs Reference
In-Depth Information
If you wish to replace several elements at one time, you can use the colon
operator. Typing
A(3,1:4) = [1 3 3 5];
replaces all elements of the third row of matrix
A
. The colon operator is used
for other several things in MATLAB, for instance as an abbreviation for
entering matrix elements such as
c = 0 : 10
which creates a row vector containing all integers from 0 to 10. The corre-
sponding MATLAB response is
c =
0 1 2 3 4 5 6 7 8 9 10
Note that this statement creates 11 elements, i.e., the integers from 1 to 10
and the zero. A common error while indexing matrices is the ignorance of
the zero and therefore expecting 10 instead of 11 elements in our example.
We can check this from the output of
whos
.
Name Size Bytes Class
A 4x4 128 double array
b 1x1 8 double array
c 1x11 88 double array
Grand total is 28 elements using 224 bytes
The above command only creates integers, i.e., the interval between the
vector elements is one. However, an arbitrary interval can be defi ned, for
example 0.5. This is later used to create evenly-spaced time axes for time
series analysis for instance.
c = 1 : 0.5 : 10;
c =
Columns 1 through 6
1.0000 1.5000 2.0000 2.5000 3.0000 3.5000
Columns 7 through 12
4.0000 4.5000 5.0000 5.5000 6.0000 6.5000
Columns 13 through 18
7.0000 7.5000 8.0000 8.5000 9.0000 9.5000
Column 19
10.0000
The display of the values of a variable can be interrupted by pressing
Ctrl-C
(
Control-C
) on the keyboard. This interruption only affects the output in
the Command Window, whereas the actual command is processed before
displaying the result.
