HP 48gII Graphing Calculator Manuel d'utilisateur télécharger pdf (Page 513)

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

DEFINE(‘g(X) = IFTE(X<1,X,2-X)’)

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

for the Fourier

series 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

= 0.5. If we now want to obtain a generic

expression for the coefficient c

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HP 48gII Graphing Calculator Manuel d'utilisateur Page 513