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: ring_of_differential_difference_operators : Macro Operators : ring_def


string ring_of_difference_operators
!!! OBSOLETE !!!
This command has not been maintained since 1996. So, there may be
troubles if it is used with new features of kan/sm1.
This command is used to define a ring of difference operators 
with the macros define_ring, weight_vector and elimination_order.
The user cannot use the variable names h, e, H and E.
cf. show_ring, system_variable --- CurrentRing
    print_switch_status, switch_function
Example: [(x,y,z) ring_of_difference_operators (Ex,Ey) elimination_order 0] define_ring
         Ex,Ey, and Ez are corresponding difference operators to the 
         space variables x, y and z ( Ex x = (x+1) Ex).

Nobuki Takayama 平成17年2月10日