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all - Determine whether all array elements are nonzero or true

Syntax

B = all(A)
B = all(A, dim)

Description

B = all(A) tests whether all the elements along various dimensions of an array are nonzero or logical 1 (true).

If A is a vector, all(A) returns logical 1 (true) if all the elements are nonzero and returns logical 0 (false) 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 logical 1's and 0's.

If A is a multidimensional array, all(A) treats the values along the first nonsingleton dimension as vectors, returning a logical condition for each vector.

B = all(A, dim) tests along the dimension of A specified by scalar dim.

Examples

Given

A = [0.53 0.67 0.01 0.38 0.07 0.42 0.69] 

then B = (A < 0.5) returns logical 1 (true) only where A is less than one half:

0   0   1   1   1   1   0

The 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 =
   0

See Also

any, logical operators (elementwise and short-circuit), relational operators, colon

Other functions that collapse an array's dimensions include max, mean, median, min, prod, std, sum, and trapz.

alim

allchild

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