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1
T
) (
exp(
c
f
t
n
0
T
Function FOURIER provides the coefficient c
Fourier series given the function f(t) and the value of n. The function FOURIER
requires you to store the value of the period (T) of a T-periodic function into
the CAS variable PERIOD before calling the function. The function FOURIER is
available in the DERIV sub-menu within the CALC menu („Ö).
Fourier series for a quadratic function
Determine the coefficients c
T = 2. (Note: Because the integral used by function FOURIER is calculated in
the interval [0,T], while the one defined earlier was calculated in the interval
[-T/2,T/2], we need to shift the function in the t-axis, by subtracting T/2 from t,
i.e., we will use g(t) = f(t-1) = (t-1)
Using the calculator in ALG mode, first we define functions f(t) and g(t):
Next, we move to the CASDIR sub-directory under HOME to change the value
of variable PERIOD, e.g., „ (hold) §`J @) C ASDI `2 K
@PERIOD `
Return to the sub-directory where you defined functions f and g, and calculate
the coefficients (Accept change to Complex mode when requested):
2
π
i
n
)
,
t
dt
n
T
of the complex-form of the
n
, c
, and c
for the function f(t) = t
0
1
2
2
+(t-1).)
,...,
, 2
1
0 ,
1 ,
2 ,
,...
.
2
+t, with period
Page 16-29
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