S_I _ _ _ _ _ _ _ _ _ _ _ _ operator

The s_i operator returns the Sine Integral function si.

syntax:

examples:

s_i(xx); 

  (2*Si(xx) - pi) / 2 


df(s_i(x),x); 

  sin(x) / x

The operator name s_i is simplified towards SI. Since REDUCE is not case sensitive by default the name ``si'' can't be used.