Why does my plot of the Blackman window not match everyone else's in literature? I've seen the plot for Blackman window as so in a bunch of books, as on this website:



But plotting the same equation on Wolfram Alpha yields a different plot:



Why is their graph not centered around 0? And why is their peak at y=1?
There is a missing $2\times$ factor inside the second cosine, and you get a centered $201$ point windows with the change of variable $x-100$. See at Wolfram:

$$ 0.42 - 0.5*\cos\left(2\pi\frac{x-100}{200}\right) + 0.08 \cos\left(4\pi\frac{x-100}{200}\right)\,.$$