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: ring_of_differential_operators : Macro Operators : ring_of_difference_operators


[string1 string2]  ring_of_differential_difference operators
This command is used to define a ring of differential-difference operators 
with the macros define_ring, weight_vector and elimination_order.
string1 is a set of variables for differential operators.
string2 is a set of variables for difference operators.
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) (s)] ring_of_differential_difference_operators 
          [[(Es) 1] [(s) 1]] weight_vector 0] define_ring
         Dx and Dy are corresponding differential operators to the 
         space variables x and y.  Try show_ring to see the commutation

Nobuki Takayama 平成17年2月10日