logical - Convert numeric values to logical

Syntax

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 that is the same size as A, returns the values of A at the indices where the real part of B is nonzero.

A(B), where B is a logical array that is smaller than A, returns the values of column vector A(:) at the indices where the real part of column vector B(:) is nonzero.

Tips

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

false | islogical | Logical Operators: Elementwise | Logical Operators: Short-circuit | true

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