ABSTRACT

The simplest periodic function is the sine (or cosine) function, A sin(ωt + α) (or A cos(ωt + α)), where ω is the angular frequency related to the period by the relationship

ω =

pi2 T

(9.1)

(quantity f = 1/T is called frequency, constant α is called phase). With these simple periodic functions more complex periodic functions can be con-

structed, as was noted by the French mathematician Joseph Fourier. For example, if we add the functions

= = ω + α = ω + α

= ω + α

, sin( ), sin(2 ),

sin(3 ),...