fix

src/function.rs

@@ -80,6 +80,7 @@ impl FunctionEntry {
             self.func_str = func_str.clone();
             self.function = BackingFunction::new(&func_str);
             self.output.invalidate_whole();
+            self.output.invalidate_points();
         }
 
         self.derivative = derivative;
@@ -149,10 +150,12 @@ impl FunctionEntry {
         } else {
             self.output.invalidate_back();
             self.output.invalidate_derivative();
-            self.min_x = min_x;
-            self.max_x = max_x;
             self.pixel_width = pixel_width;
         }
+
+        self.min_x = min_x;
+        self.max_x = max_x;
+        self.output.invalidate_points();
     }
 
     pub fn run_back(&mut self) -> (Vec<Value>, Option<(Vec<Bar>, f64)>, Option<Vec<Value>>) {

src/function_output.rs

@@ -42,6 +42,11 @@ impl FunctionOutput {
 
     pub fn invalidate_derivative(&mut self) { self.derivative = None; }
 
+    pub fn invalidate_points(&mut self) {
+        self.extrema = None;
+        self.roots = None;
+    }
+
     pub fn display(
         &self, plot_ui: &mut PlotUi, func_str: &str, derivative_str: &str, step: f64,
         derivative_enabled: bool,