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-rw-r--r--src/sinusoid.rs98
1 files changed, 59 insertions, 39 deletions
diff --git a/src/sinusoid.rs b/src/sinusoid.rs
index cc9c20c..fe8b3ad 100644
--- a/src/sinusoid.rs
+++ b/src/sinusoid.rs
@@ -1,9 +1,12 @@
use std::cmp::{PartialOrd};
use ::num_traits::{Trig, ArithmeticOps, FractionOps};
-// generic number type, but realistically it's only useful for
-// floats. Maybe also complex<float>
-
+/// A data structure representing a sinusoid. AKA the sin or cos functions.
+///
+/// The general formula for a sinusoid is A cos(2πf + θ)
+///
+/// The number type is generic, but realistically it's only useful for
+/// floats.
pub struct Sinusoid<T> {
amplitude: T,
frequency: T,
@@ -20,20 +23,72 @@ impl<T> Sinusoid<T> {
}
}
impl<T> Sinusoid<T> where T: FractionOps + Copy {
+ /// The period is the time taken for each repetition of the
+ /// sinusoid
+ ///
+ /// ```
+ /// use worthe_signals::sinusoid::Sinusoid;
+ /// use std::f32;
+ ///
+ /// let sinusoid = Sinusoid::new(1.0 as f32, 0.5, 0.0);
+ /// assert!((sinusoid.period()-2.0) < f32::EPSILON);
+ /// ```
pub fn period(&self) -> T {
self.frequency.recip()
}
}
impl<T> Sinusoid<T> where T: FractionOps + ArithmeticOps + Trig + Copy {
+ /// Frequency can be considered in terms of the signal's number of
+ /// repetitions per second (referred to just as the frequency), or
+ /// the frequency in radians.
+ /// ```
+ /// use worthe_signals::sinusoid::Sinusoid;
+ /// use std::f32;
+ ///
+ /// let sinusoid = Sinusoid::new(1.0 as f32, 1.0, 0.0);
+ /// assert!((sinusoid.radial_frequency()-2.0*f32::consts::PI) < f32::EPSILON);
+ /// ```
pub fn radial_frequency(&self) -> T {
T::two_pi()*self.frequency
}
+
+ /// A sinusoid can be sampled to get its value at a given point in
+ /// time.
+ ///
+ /// ```
+ /// use worthe_signals::sinusoid::Sinusoid;
+ /// use std::f32;
+ ///
+ /// let sinusoid = Sinusoid::new(1.0 as f32, 1.0, -f32::consts::FRAC_PI_2); //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);
+ /// ```
pub fn sample(&self, t: T) -> T {
(self.radial_frequency()*(t%self.period()) + self.phase).cos() * self.amplitude
}
}
impl<T> Sinusoid<T> where T: FractionOps + ArithmeticOps + From<u16> + Trig + Copy + PartialOrd {
- //inclusive of start, exclusive of end
+ /// Sometimes, it's useful to sample at all of the points in a range
+ ///
+ /// Start value is inclusive. End value is exclusive.
+ ///
+ /// ```
+ /// use worthe_signals::sinusoid::Sinusoid;
+ /// use std::f32;
+ ///
+ /// let sinusoid = Sinusoid::new(1.0 as f32, 1.0, -f32::consts::FRAC_PI_2); //AKA sin
+ /// let samples = sinusoid.sample_range(0.0, 100.0, 4.0);
+ /// assert_eq!(samples.len(), 400);
+ /// for i in (0..100).map(|i| i*4) {
+ /// assert!((samples[i+0]-0.0) < f32::EPSILON, "Sample {} was {}", i+0, samples[i+0]);
+ /// assert!((samples[i+1]-1.0) < f32::EPSILON, "Sample {} was {}", i+1, samples[i+1]);
+ /// assert!((samples[i+2]-0.0) < f32::EPSILON, "Sample {} was {}", i+2, samples[i+2]);
+ /// assert!((samples[i+3]+1.0) < f32::EPSILON, "Sample {} was {}", i+3, samples[i+3]);
+ /// }
+ /// ```
pub fn sample_range(&self, start: T, end: T, sample_rate: T) -> Vec<T> {
let mut result = Vec::new();
let mut i: u16 = 0;
@@ -55,39 +110,4 @@ 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::FRAC_PI_2); //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);
- }
-
- #[test]
- fn sample_range() {
- let sinusoid = Sinusoid::new(1.0 as f32, 1.0, -f32::consts::FRAC_PI_2); //AKA sin
- let samples = sinusoid.sample_range(0.0, 100.0, 4.0);
- println!("Epsilon is {}", f32::EPSILON);
- assert_eq!(samples.len(), 400);
- for i in (0..100).map(|i| i*4) {
- assert!((samples[i+0]-0.0) < f32::EPSILON, "Sample {} was {}", i+0, samples[i+0]);
- assert!((samples[i+1]-1.0) < f32::EPSILON, "Sample {} was {}", i+1, samples[i+1]);
- assert!((samples[i+2]-0.0) < f32::EPSILON, "Sample {} was {}", i+2, samples[i+2]);
- assert!((samples[i+3]+1.0) < f32::EPSILON, "Sample {} was {}", i+3, samples[i+3]);
- }
- }
}