MATLAB Functions | Help Desk |
find
Find indices and values of nonzero elements
k = find(x) [i,
j] = find(X) [i,
j,
v] = find(X)
k = find(X)
returns the indices of the array x
that point to nonzero elements. If none is found, find
returns an empty matrix.
[i,j] = find(X)
returns the row and column indices of the nonzero entries in the matrix X
. This is often used with sparse matrices.
[i,j,v] = find(X)
returns a column vector v
of the nonzero entries in X
, as well as row and column indices.
In general, find(X)
regards X
as X(:)
, which is the long column vector formed by concatenating the columns of X
.
[i,j,v] = find(X~=0)
produces a vector v
with all 1
s, and returns the row and column indices.
Some operations on a vector
x = [11 0 33 0 55]'; find(x) ans = 1 3 5 find(x == 0) ans = 2 4 find(0 < x & x < 10*pi)And on a matrix
M = magic(3) M = 8 1 6 3 5 7 4 9 2 [i,j,m] = find(M > 6) i = j = m = 1 1 1 2 2 1 3 3 1The relational operators
<
, <=
,>
,>=
,==
, ~=
, and:
nonzeros
Nonzero matrix elements
sparse
Create sparse matrix