From d4ab383a1b429b445f485c369f6aa7b72ce6d284 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <github@thinkyhead.com>
Date: Tue, 23 Jan 2018 16:18:54 -0600
Subject: [PATCH] Lightly optimize arc length calculation

---
 Marlin/Marlin_main.cpp | 3 ++-
 Marlin/planner.cpp     | 3 +--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 808da5842de..b3d9bf33609 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -12880,7 +12880,8 @@ void prepare_move_to_destination() {
     if (angular_travel == 0 && current_position[p_axis] == cart[p_axis] && current_position[q_axis] == cart[q_axis])
       angular_travel = RADIANS(360);
 
-    const float mm_of_travel = HYPOT(angular_travel * radius, FABS(linear_travel));
+    const float flat_mm = radius * angular_travel,
+                mm_of_travel = linear_travel ? HYPOT(flat_mm, linear_travel) : flat_mm;
     if (mm_of_travel < 0.001) return;
 
     uint16_t segments = FLOOR(mm_of_travel / (MM_PER_ARC_SEGMENT));
diff --git a/Marlin/planner.cpp b/Marlin/planner.cpp
index adbf1425074..7486e3bd56f 100644
--- a/Marlin/planner.cpp
+++ b/Marlin/planner.cpp
@@ -362,7 +362,7 @@ void Planner::recalculate_trapezoids() {
   }
 }
 
-/*
+/**
  * Recalculate the motion plan according to the following algorithm:
  *
  *   1. Go over every block in reverse order...
@@ -392,7 +392,6 @@ void Planner::recalculate() {
   recalculate_trapezoids();
 }
 
-
 #if ENABLED(AUTOTEMP)
 
   void Planner::getHighESpeed() {