ABSTRACT
The basis of a Fourier series is that all functions of practical significance which are defined in the interval − π ≤ x ≤ π https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429294402/968186b9-ffa4-4f2b-aa54-7fc58a604561/content/eq5912.tif"/> can be expressed in terms of a convergent trigonometric series of the form: f ( x ) = a 0 + a 1 cos x + a 2 cos 2 x + a 3 cos 3 x + ⋯ ⋅ + b 1 sin x + b 2 sin 2 x + b 3 sin 3 x + ⋅ ⋅ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429294402/968186b9-ffa4-4f2b-aa54-7fc58a604561/content/eq5913.tif"/>
