# Fourier Series For A Triangular Wave - HP 50g User Manual

Graphing calculator.

periodicity in the graph of the series. This periodicity is easy to visualize by
expanding the horizontal range of the plot to (-0.5,4):

## Fourier series for a triangular wave

Consider the function
which we assume to be periodic with period T = 2. This function can be
defined in the calculator, in ALG mode, by the expression
If you started this example after finishing example 1 you already have a value
of 2 stored in CAS variable PERIOD. If you are not sure, check the value of this
variable, and store a 2 in it if needed. The coefficient c
is calculated as follows:
The calculator will request a change to Approx mode because of the integration
of the function IFTE() included in the integrand. Accepting, the change to
Approx produces c
the coefficient c
n
g
(
x
)
DEFINE('g(X) = IFTE(X<1,X,2-X)')
= 0.5. If we now want to obtain a generic expression for
0
use:
x
,
if
0
x
2
x
,
if
1
x
1
2
for the Fourier series
0
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