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Revision difference : Fourier coefficients
Version 2 Version 1
Let $f$ be a Riemann integrable function from $[\pi,\pi]$ to $R$. Then the numbers Let $f$ be a Riemann integrable function from $[\pi,\pi]$ to $\sR$. Then the numbers
$$a_0^f = \frac{1}{2\pi}\int_{-\pi}^{\pi}f(x)dx,$$ $$a_0^f = \frac{1}{2\pi}\int_{-\pi}^{\pi}f(x)dx,$$
$$a_n^f = \frac{1}{\pi}\int_{-\pi}^{\pi}f(x)cos(nx)dx,$$ $$a_n^f = \frac{1}{\pi}\int_{-\pi}^{\pi}f(x)cos(nx)dx,$$
$$b_n^f = \frac{1}{\pi}\int_{-\pi}^{\pi}f(x)sin(nx)dx$$ $$b_n^f = \frac{1}{\pi}\int_{-\pi}^{\pi}f(x)sin(nx)dx$$
are called the Fourier coefficients of the function $f.$ are called the Fourier coefficients of the function $f.$
The trigonometric series The trigonometric series
$$ a_0^f + \sum_{n=1}^{\infty}(a_n^fcos(nx)+b_n^fsin(nx))$$ is called the trigonometric series of the function $f$, or Fourier series of the function $f.$ $$ a_0^f + \sum_{n=1}^{\infty}(a_n^fcos(nx)+b_n^fsin(nx))$$ is called the trigonometric series of the function $f$, or Fourier series of the function $f.$