25.99. ISDEFINED

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This function can be used to determine whether an expression is defined or undefined (aka undef). If the argument is a defined value then the function returns true, otherwise the function returns false.

This function is the counter function of ISUNDEF.

See also ISARRAY, ISSTRING, ISINTEGER, ISREAL, ISNUMERIC, ISUNDEF, ISEMPTY, TYPE.


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