simplify newtons_method_helper

Wohoo!! 1000th commit, I know this specific commit is super small, but the number of total commits is a large milestone.

src/misc.rs

@@ -58,7 +58,8 @@ pub fn newtons_method_helper(
 		.tuple_windows()
 		.filter(|(prev, curr)| prev.y.is_finite() && curr.y.is_finite())
 		.filter(|(prev, curr)| prev.y.signum() != curr.y.signum())
-		.map(|(start, _)| newtons_method(f, f_1, start.x, range, threshold))
+		.map(|(start, _)| start.x)
+		.map(|x| newtons_method(f, f_1, x, range, threshold))
 		.filter(|x| x.is_some())
 		.map(|x| unsafe { x.unwrap_unchecked() })
 		.collect()