problem of using global declaration:-)

[Yip Fai]

Hi,
I have a question about using global declaration. When the global
variable is operated by isempty inside a function, octave tell me that
the variable is undefined. However, if the variable is defined as
following.

global a = [];

inside the function, the operation goes on without error. But this
declaration causes drawback of using a function whenever I want. Is
there any better way to declare a global variable?

Thanks

Ken