| 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 1s and 0s.
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.
Given,
A = [0.53 0.67 0.01 0.38 0.07 0.42 0.69]
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