fix: Address PR feedback

Prevent division by zero when min equals max value

Also improves angle calculations using TAU constant and adds NaN validation.
Also fix doc

examples/example_knob.rs

@@ -122,7 +122,7 @@ impl eframe::App for KnobExample {
                 );
 
                 ui.add(
-                    Knob::new(&mut self.blue_value, 0.0, 100.0, egui_knob::KnobStyle::Dot)
+                    Knob::new(&mut self.blue_value, 0.0, 100., egui_knob::KnobStyle::Dot)
                         .with_label("Top", egui_knob::LabelPosition::Top)
                         .with_colors(
                             egui::Color32::from_rgb(30, 30, 80),

src/lib.rs

@@ -44,7 +44,16 @@ pub struct Knob<'a> {
     label_offset: f32,
     label_format: Box<dyn Fn(f32) -> String>,
     step: Option<f32>,
+
+    /// Minimum angle in radians.  
+    /// Specifies the lower bound of the knob's rotation.  
+    /// Expected range: 0.0 to TAU. Values outside this range are allowed if your use case requires it.
     min_angle: f32,
+
+    /// Maximum angle in radians.  
+    /// Specifies the upper bound of the knob's rotation.
+    /// Can be any value > `min_angle`
+    /// range `max_angle` - `min_angle` > TAU is allowed but will induce multi-turn
     max_angle: f32,
 }
 
@@ -73,6 +82,8 @@ impl<'a> Knob<'a> {
             label_offset: 1.0,
             label_format: Box::new(|v| format!("{:.2}", v)),
             step: None,
+
+            // Hardcode those two angles to ENSURE backward compatibility
             min_angle: -std::f32::consts::PI,
             max_angle: std::f32::consts::PI * 0.5,
         }
@@ -81,7 +92,7 @@ impl<'a> Knob<'a> {
     /// Sets the angular sweep range of the knob
     ///
     /// This controls where the knob starts and how far it can rotate. By default,
-    /// knobs start at the bottom-left (135°) and sweep 270° clockwise to bottom-right.
+    /// knobs start at the left (180°) and sweep 270° clockwise to bottom.
     ///
     /// # Arguments
     /// * `start_angle_normalized` - Starting position as fraction of full circle:
@@ -95,12 +106,20 @@ impl<'a> Knob<'a> {
     ///   - `0.75` = three-quarter turn (270°)
     ///   - `1.0` = full turn (360°)
     ///   - Values > 1.0 create multi-turn knobs
+    ///   - Negative values are clamped to 0.0
+    ///
+    /// Note: the start angle is offset by PI/2 so that `0.0` is at the bottom (6 o'clock)
     pub fn with_sweep_range(mut self, start_angle_normalized: f32, range: f32) -> Self {
+        if start_angle_normalized.is_nan() || range.is_nan() {
+            // Invalid input, return unchanged
+            return self;
+        }
+
         self.min_angle =
-            start_angle_normalized.rem_euclid(1.) * f32::consts::PI * 2. + f32::consts::PI / 2.;
+            start_angle_normalized.rem_euclid(1.) * f32::consts::TAU + f32::consts::PI / 2.;
 
         // A range of 1. represent a full turn
-        self.max_angle = self.min_angle + range.max(0.) * 2. * f32::consts::PI;
+        self.max_angle = self.min_angle + range.max(0.) * f32::consts::TAU;
         self
     }
 
@@ -242,8 +261,15 @@ impl Widget for Knob<'_> {
 
         let center = knob_rect.center();
         let radius = knob_size.x / 2.0;
-        let angle = self.min_angle
-            + (*self.value - self.min) / (self.max - self.min) * (self.max_angle - self.min_angle);
+        let angle = if self.min == self.max {
+            // If min == max, just return min angle
+            // That's a edge case, using a 0 range knob is pretty useless
+            self.min_angle
+        } else {
+            self.min_angle
+                + (*self.value - self.min) / (self.max - self.min)
+                    * (self.max_angle - self.min_angle)
+        };
 
         painter.circle_stroke(
             center,