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| -rw-r--r-- | Problem Set 2.page | 1 |
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diff --git a/Problem Set 2.page b/Problem Set 2.page index de38296..ed138ec 100644 --- a/Problem Set 2.page +++ b/Problem Set 2.page @@ -44,6 +44,7 @@ $\sin x = \frac{e^{ix}-e^{-ix}}{2}$, $\sin^4 x = \frac{{( e^{ix}-e^{-ix} )}^4}{16}$ $= \frac{e^{i 4x}+e^{-i 4x}-4 e^{i 2x} -4 e^{-i 2x}+6}{16}$. +\\ If we express any periodic function $f(x)$ as $f(x) = \sum a_n f_n(x)$, where $f_n(x) = \frac{e^{inx}}{\sqrt{2\pi}}$ and $f_0(x) = \frac{1}{\sqrt{2\pi}}$, |