Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-oxford/2017/prelims/mathematics-v/4/b/solution

The real Fourier series of is written
where the Fourier coefficients are
By part (a)(i), any other interval of length gives the same Fourier coefficients, because each integrand is a periodic function with period . The notation associates with its Fourier series; existence of the integrals alone does not assert pointwise convergence.

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