fix(math): correct and simplify some math functions

Signed-off-by: Riccardo Gallo <[email protected]>
astarte-platform · Nov 7, 2024 · ba6c64d · ba6c64d
1 parent 67bf216
commit ba6c64d
Showing 1 changed file with 11 additions and 9 deletions.
diff --git a/src/math.rs b/src/math.rs
@@ -57,7 +57,9 @@ pub enum MathFunction {
     Saw,
     /// Rect
     Rect,
-    /// Sinc
+    /// Normalized Sinc
+    ///
+    /// sinc(x) = sin(PI*x) / (PI*x)
     Sinc,
     /// Random value
     Random,
@@ -122,14 +124,15 @@ fn sin(value: f64) -> f64 {
 }
 
 fn noise_sin(value: f64) -> f64 {
-    value.sin() + rand::random::<f64>() / f64::MAX * 0.2
+    value.sin() + random()
 }
 
 fn random_spikes_sin(value: f64) -> f64 {
-    if value.sin() + rand::random::<f64>() / f64::MAX * 0.1 + rand::random::<f64>() / f64::MAX * 0.1
-        > 0.999
-    {
-        100.0
+    let v = noise_sin(value);
+
+    //  spike(x) = 1, if 0 ≤ x < 1, 0 elsewhere
+    if (0.0..0.999).contains(&v) {
+        1.0
     } else {
         0.0
     }
@@ -156,7 +159,6 @@ fn rect(value: f64) -> f64 {
     }
 }
 
-/// Normalized sinc function: sin(PI*x) / (PI*x)
 fn sinc(value: f64) -> f64 {
     if value == 0.0 {
         1.0
@@ -167,11 +169,11 @@ fn sinc(value: f64) -> f64 {
 }
 
 fn random() -> f64 {
-    rand::random::<f64>() / f64::MAX
+    rand::random::<f64>()
 }
 
 fn random_interval() -> f64 {
-    (rand::random::<f64>() % 600.0) * 1000.0 + (rand::random::<f64>() % 1000.0)
+    (random() * 1000.0) % 600.0 + random()
 }
 
 fn default(value: f64) -> f64 {