HP 49g+ - Manual (Page 139)

Page 11-4
Please notice that functions SIGMAVX and SIGMA are designed for
integrands that involve some sort of integer function like the factorial (!)
function shown above. Their result is the so-called discrete derivative, i.e.,
one defined for integer numbers only.
Definite integrals
In a definite integral of a function, the resulting anti-derivative is evaluated at
the upper and lower limit of an interval (a,b) and the evaluated values
subtracted. Symbolically, we write
), ( ) ( ) ( a F b F dx x f
b
a
− = ∫
where f(x) = dF/dx.
To calculate definite integrals of functions using the CAS variable VX
(typically, ‘X’), use function PREVAL(f(x),a,b). For example,
Infinite series
A function f(x) can be expanded into an infinite series around a point x=x
0
by
using a Taylor’s series, namely,