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orthogonal functions

Two functions whose inner product is zero.

Two functions $f,g$ on $[a,b]$ are orthogonal when $\langle f,g\rangle=\int_a^bf(x)g(x)\,dx=0$ -- the function-space analog of two perpendicular vectors.

Examples

$\sin(mx)$ and $\sin(nx)$ are orthogonal on $[-\pi,\pi]$ for any distinct integers $m,n$ .