MATLAB Function Reference

logical

Convert numeric values to logical

Syntax

• K = logical(A)
  

Description

K = logical(A) returns an array that can be used for logical indexing or logical tests.

A(B), where B is a logical array, returns the values of A at the indices where the real part of B is nonzero. B must be the same size as A.

Remarks

Most arithmetic operations remove the logicalness from an array. For example, adding zero to a logical array removes its logical characteristic. A = +A is the easiest way to convert a logical array, A, to a numeric double array.

Logical arrays are also created by the relational operators (==,<,>,~, etc.) and functions like any, all, isnan, isinf, and isfinite.

Examples

Given A = [1 2 3; 4 5 6; 7 8 9], the statement B = logical(eye(3)) returns a logical array

• B =
     1   0   0
     0   1   0
     0   0   1
  

which can be used in logical indexing that returns A's diagonal elements:

• A(B)
  
  ans =
       1
       5
       9
  

However, attempting to index into A using the numeric array eye(3) results in:

• A(eye(3))
  ??? Subscript indices must either be real positive integers or 
  logicals.
  

See Also

islogical, logical operators (elementwise and short-circuit),

log2

Logical Operators: Elementwise & | ~

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