Projections of functions and bases

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SUMMARY

The discussion focuses on the projection of the function ##f(x) = x## onto the basis ##e = \{ 1/\sqrt{2 \pi}, 1/\sqrt{\pi}\sin x, 1/\sqrt{2 \pi}\cos x \}## in the space ##L_2[0,2\pi]##. The proposed solution involves calculating the integral ##e \cdot \int_0^{2\pi} e f(x) \, dx = \pi - 2 \sin x##, which is presented as a valid approach to finding the projection ##Pr_e f##. The discussion emphasizes the importance of understanding function projections in Hilbert spaces.

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  • Knowledge of integral calculus, specifically definite integrals
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Homework Statement


On ##L_2[0,2\pi]## where ##e = \{ 1/\sqrt{2 \pi},1/\sqrt{\pi}\sin x,1/\sqrt{2 \pi}\cos x \}##. Given ##f(x) = x##, find ##Pr_e f##.

Homework Equations


See solution.

The Attempt at a Solution


I take $$e \cdot \int_0^{2\pi} e f(x) \, dx = \pi - 2 \sin x.$$ Look correct?
 
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That's how I'd approach it.
 
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