exists

exists — checks variable existence

Calling sequence

exists(name [,where])

`name`	: a character string
`where`	: an optional character string with default value `'all'`

exists(name) returns 1 if the variable named name exists and 0 otherwise.

Caveats: a function which uses exists may return a result which depends on the environment!

exists(name,'local') returns 1 if the variable named name exists in the local environment of the current function and 0 otherwise.



deff('foo(x)',..
['disp([exists(''a12''),exists(''a12'',''local'')])'
 'disp([exists(''x''),exists(''x'',''local'')])'])
foo(1)
a12=[];foo(1)