Principal Web Developer at Freedom of the Press Foundation
Published
Edited
Apr 20, 2022
9 stars
sineWave = (period = 1, amplitude = 2) => x => amplitude * Math.sin(x * 2 * Math.PI / period)
squareWave = (period = 1, amplitude = 2) => x => amplitude * Math.sign(Math.sin(x * 2 * Math.PI / period))
triangleWave = (period = 1, amplitude = 2) => (
x => Math.abs(x / period + 0.25 - Math.floor(x / period + .75)) * 4 * amplitude - amplitude
)
sawtoothWave = (period = 1, amplitude = 2) => x => (2 * amplitude / period) * mod(x, period) - amplitude
functions = new Map([
['sine', sineWave(period, amplitude)],
['square', squareWave(period, amplitude)],
['triangle', triangleWave(period, amplitude)],
['sawtooth', sawtoothWave(period, amplitude)],
])
samples = mapMap(functions, fn => build_samples(fn, -4, 4, { N: 500 }))
capfirst = str => str.slice(0, 1).toUpperCase() + str.slice(1)
mod = (n, m) => ((n % m) + m) % m
mapMap = (map, fn) => new Map(Array.from(map).map(([key, val]) => [key, fn(val)]))
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