EI _ _ _ _ _ _ _ _ _ _ _ _ operator

The Ei operator returns the Exponential Integral function.

syntax:

examples:

df(ei(x),x); 

   x
  e
  ---
  x


on rounded; 

Ei(0.35); 

  - 0.0894340019184

The numeric values for the operator Ei are computed via t he power series representation, which limits the argument range.