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use std;
use std::ops::{Add, Sub, Mul, Div, Neg};
use ::num_traits::{Trig, Pow, Float};
// generic number type, but realistically it's only useful for
// floats. Maybe also complex<float>
pub struct Sinusoid<T> {
amplitude: T,
frequency: T,
phase: T
}
impl<T> Sinusoid<T> {
pub fn new(amplitude:T, frequency: T, phase: T) -> Sinusoid<T> {
Sinusoid {
amplitude: amplitude,
frequency: frequency,
phase: phase
}
}
}
impl<T> Sinusoid<T> where T: Float + Copy {
pub fn period(&self) -> T {
self.frequency.recip()
}
}
impl<T> Sinusoid<T> where T: Float + Add<Output=T> + Mul<Output=T> + From<u8> + Trig + Copy + std::fmt::Display {
pub fn radial_frequency(&self) -> T {
(T::from(2))*T::PI()*self.frequency
}
pub fn sample(&self, t: T) -> T {
(self.radial_frequency()*t + self.phase).cos() * self.amplitude
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::f32;
#[test]
fn period() {
let sinusoid = Sinusoid::new(1.0 as f32, 0.5, 0.0);
assert!((sinusoid.period()-2.0) < f32::EPSILON);
}
#[test]
fn radial_f() {
let sinusoid = Sinusoid::new(1.0 as f32, 1.0, 0.0);
assert!((sinusoid.radial_frequency()-2.0*f32::consts::PI) < f32::EPSILON);
}
#[test]
fn sample() {
let sinusoid = Sinusoid::new(1.0 as f32, 1.0, -f32::consts::PI/2.0); //AKA sin
assert!((sinusoid.sample(0.0)-0.0) < f32::EPSILON);
assert!((sinusoid.sample(0.25)-1.0) < f32::EPSILON);
assert!((sinusoid.sample(0.5)-0.0) < f32::EPSILON);
assert!((sinusoid.sample(0.75)+1.0) < f32::EPSILON);
assert!((sinusoid.sample(1.0)-0.0) < f32::EPSILON);
}
}
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