Multiple series

Since MathMate allows nested procedures, it is possible to compute multiple sums. To compute them, use either Calculator mode or Summation mode. The following example shows how to compute a double sum using the Calculator mode.

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: