Graphics Programs Reference
In-Depth Information
Logical operators
&
AND
|
OR
~
NOT
xor
EXCLUSIVE OR
any
True if any element is non-zero
all
True if all elements are non-zero
We continue the previous example and use
find
to plot the part of
the peaks function that lies between
y
= 20 and
y
= 40:
clf
ind = find(20<=y & y<=40);
plot(x,y,x(ind),y(ind),'o')
grid
When used with one output argument,
find
assumes that the input is
a vector. When the input is a matrix
find
first strings out the elements
as a single column vector and returns the corresponding indices. As an
example we consider the spiral matrix:
>> s = spiral(3)
s=
7 8 9
6 1 2
5 4 3
We find the elements of
s
less than 6:
>> s<6
ans =
0
0
0
0
1
1
1
1
1
>> find(s<6)
ans =
3
5
6
8
9
The result of
find
is a vector of indices of
s
counted down the first col-
umn, then the second, and then the third. The following example shows
how the results of the find command can be used to extract elements
from a matrix that satisfy a logical test:
