Programming

Creating a Logical Array

One way of creating an array of logicals is to just enter a true or false value for each element. The true function returns logical one; the false function returns logical zero:

• x = [true, true, false, true, false];
  

Logical Operations on an Array

You can also perform some logical operation on an array that yields an array of logicals:

• x = magic(4) >= 9
  x =
       1     0     0     1
       0     1     1     0
       1     0     0     1
       0     1     1     0
  

The MATLAB functions that have names beginning with is (e.g., ischar, issparse) also return a logical value or array:

• a = [2.5 6.7 9.2 inf 4.8];
  
  isfinite(a)
  ans =
       1     1     1     0     1
  

This table shows some of the MATLAB operations that return a logical true or false.

Function	Operation
true, false	Setting value to true or false
logical	Numeric to logical conversion
& (and), | (or), ~ (not), xor, any, all	Logical operations
&&, ||	Short-circuit AND and OR
== (eq), ~= (ne), < (lt), > (gt), <= (le), >= (ge)	Relational operations
All is* functions, cellfun	Test operations
strcmp, strncmp, strcmpi, strncmpi	String comparisons

Sparse Logical Arrays

Logical arrays can also be sparse as long as they have no more than two dimensions:

• x = sparse(magic(20) > 395)
  x =
     (1,1)        1
     (1,4)        1
     (1,5)        1
    (20,18)       1
    (20,19)       1
  

Logical Types

How Logical Arrays Are Used

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