ALL All True Function

Section: Elementary Functions


Reduces a logical array along a given dimension by testing for all logical 1s. The general syntax for its use is
  y = all(x,d)

where x is an n-dimensions array of logical type. The output is of logical type. The argument d is optional, and denotes the dimension along which to operate. The output y is the same size as x, except that it is singular along the operated direction. So, for example, if x is a 3 x 3 x 4 array, and we all operation along dimension d=2, then the output is of size 3 x 1 x 4.

Function Internals

The output is computed via

If d is omitted, then the minimum is taken over all elements of x.


The following piece of code demonstrates various uses of the all function
--> A = [1,0,0;1,0,0;0,0,1]

A = 
 1 0 0 
 1 0 0 
 0 0 1 

We start by calling all without a dimension argument, in which case it defaults to testing all values of A

--> all(A)

ans = 
 0 0 0 

The all function is useful in expressions also.

--> all(A>=0)

ans = 
 1 1 1 

Next, we apply the all operation along the rows.

--> all(A,2)

ans =