HP 48gII - Manual (Page 510)

Page 16-32
• First, define a function c(n) representing the general term c
n
in the complex
Fourier series.
• Next, define the finite complex Fourier series, F(X,k), where X is the
independent variable and k determines the number of terms to be used.
Ideally we would like to write this finite complex Fourier series as
)
2
exp( ) ( ) , ( X
T
n i
n c k X F
k
k n
⋅
⋅ ⋅ ⋅
⋅ =
∑
− =
π
However, because the function c(n) is not defined for n = 0, we will be
better advised to re-write the expression as
+ = 0 ) 0 , , ( c c k X F
)],
2
exp( ) ( )
2
exp( ) ( [
1
X
T
n i
n c X
T
n i
n c
k
n
⋅
⋅ ⋅ ⋅
− ⋅ − + ⋅
⋅ ⋅ ⋅
⋅
∑
=
π π
Or, in the calculator entry line as:
DEFINE(‘F(X,k,c0) = c0+ Σ(n=1,k,c(n)*EXP(2*i*π*n*X/T)+
c(-n)*EXP(-(2*i* π*n*X/T))’),
where T is the period, T = 2. The following screen shots show the definition of
function F and the storing of T = 2: