HP 49g+ - Manual (Page 153)

Page 14-8
Thus, c
0
= 1/3, c
1
= ( π⋅ i+2)/ π 2 , c
2
= ( π⋅ i+1)/(2 π 2 ).
The Fourier series with three elements will be written as
g(t) ≈ Re[(1/3) + ( π⋅ i+2)/ π 2 ⋅ exp(i ⋅π⋅ t)+ ( π⋅ i+1)/(2 π 2 ) ⋅ exp(2 ⋅ i ⋅π⋅ t)].
Reference
For additional definitions, applications, and exercises on solving differential
equations, using Laplace transform, and Fourier series and transforms, as well
as numerical and graphical methods, see Chapter 16 in the calculator’s
User’s Guide.