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%LOGICAL Convert numeric values to logical. % LOGICAL(X) converts the elements of the array X into logicals, % thus returning an array that can be used for logical indexing % or logical tests. logicals can have the values 0 and 1 corresponding % to false and true, respectively. Any non-zero real element of input % array X is converted to a logical 1 while zeros in X become logical 0. % Complex values and NaNs cannot be converted to logicals and will % result in a conversion error. logical arrays can also be created % using the creation functions TRUE and FALSE. % % Because logical arrays are returned by the logical operators (&,|,~) % and the relational operators (==,~=,<,<=,>=,>), as well as by % functions like ANY, ALL, ISNAN, ISINF, ISFINITE, ISEMPTY, ISEQUAL, % etc., it is unusual to need to invoke the LOGICAL function itself. % % The term "logical indexing" refers to any indexing operation where % the index expression is a logical array, in which case the index is % treated as a mask that selects elements from the indexed array. In % essence, it is a short-hand notation for A(FIND(B)) that enables us % to simply write A(B) when B is a logical array. The result is the % elements of A at the indices where B is one. It is often convenient % to derive the index expression from the indexed data itself. For % example, the positive elements of a vector A can be obtained using % A(A>0). % % Logicals can be combined with doubles in arithmetic operations and % will produce results that are of type double. You can convert a % logical to any other numeric data type using the appropriate % conversion function. For example, double(A) converts the logical % array A into a double array. % % See also ISLOGICAL, FALSE, TRUE, RELOP, OPS. % Copyright 1984-2005 The MathWorks, Inc. % Built-in function.