ISVALID Test handle validity.
TF = ISVALID(H) performs an element-wise check for validity on the 
handle elements of H.  The result is a logical array of the same 
dimensions as H, where each element is the element-wise validity 
result.
 
A handle is invalid if it has been deleted or if it is an element
of a handle array and has not yet been initialized.
 
See also SPINW, SPINW/DELETE Help for spinw/isvalid is inherited from superclass HANDLE
Reference page in Doc Center
   doc spinw/isvalid