ABSTRACT
Trigonometric series of the form () f ( x ) = 1 2 a 0 + ∑ n = 1 ∞ ( a n cos n x + b n sin n x ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315371825/895247ed-bf4c-467d-b370-ced59759b8c3/content/eq1237.tif"/>
