Index created on view is called as indexed view or 
materialised view.
To create index on a view we should create a view 
with "schemabinding"
eg:
create view v1 with schemabinding as
select empno,ename from dbo.emp
---
while creating view with schema binding refer to table by 
default owner
---
now create index on that view
--
create clustered index i1 on v1(empno)
--
now this is called as indexed view

Creating index on views is not possible in Sybase.