Suppose we need to compute a partial sum (up to degree 10) of
the double Taylor expansion series for
exp (x+y) at the point (x,y) = (1,2). To do so, enter
the following expression:
Sum (0,10;i,Sum(0,i;j,x^j*y^(i-j)/Gam (j+1)/Gam(i+1-j)))
and click Start or press Enter.
For precision 15, you obtain
Result: 20.0796651785715
(note that exp (x+y) = exp (3) = 20.0855369231877).
See also: