MATLAB Functions | Help Desk |
all
Test to determine if all elements are nonzero
B = all(A)
B = all(A,dim
)
B = all(A)
tests whether all the elements along various dimensions of an array are nonzero or logical true (1
).
If A
is a vector, all(A)
returns logical true (1
) if all of the elements are nonzero, and returns logical false (0
) if one or more elements are zero.
If A
is a matrix, all(A)
treats the columns of A
as vectors, returning a row vector of 1
s and 0
s.
If A
is a multidimensional array, all(A)
treats the values along the first non-singleton dimension as vectors, returning a logical condition for each vector.
B = all(A,dim
)
tests along the dimension of A
specified by scalar dim
.A = [0.53 0.67 0.01 0.38 0.07 0.42 0.69]
then B = (A < 0.5)
returns logical true (1
) only where A
is less than one half:
0 0 1 1 1 1 0The
all
function reduces such a vector of logical conditions to a single condition. In this case, all(B) yields 0
.
This makes all
particularly useful in if
statements,
if all(A < 0.5)
do something
end
where code is executed depending on a single condition, not a vector of possibly conflicting conditions.
Applying the all
function twice to a matrix, as in all(all(A))
, always reduces it to a scalar condition.
all(all(eye(3))) ans = 0The logical operators:
&
, |
, ~
, and:
any
Test for any nonzeros
Other functions that collapse an array's dimensions include:
max
, mean
, median
, min
, prod
, std
, sum
, trapz