From c4b8e9c5b70c4559a58fdf7386f84bb566db8a24 Mon Sep 17 00:00:00 2001
From: Ivan Chinenov <40003182+JohnDowson@users.noreply.github.com>
Date: Sun, 28 Jun 2020 19:38:17 +0300
Subject: [PATCH] Improve note to frequency conversion

```8 * pow(1.0594630943592952645618252949463, nNoteID);```
was off by about 10hz on my system, while also being ever so slightly slower than this formula
---
 main4.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/main4.cpp b/main4.cpp
index 1c35e37..b62fde3 100644
--- a/main4.cpp
+++ b/main4.cpp
@@ -155,7 +155,9 @@ namespace synth
 		switch (nScaleID)
 		{
 		case SCALE_DEFAULT: default:
-			return 8 * pow(1.0594630943592952645618252949463, nNoteID);
+			// n/12th root of 2 * A=440 where n is distance from A4 in semitones
+			// n =  NoteID - 69 as A4 is midi note 69
+			return pow(2.0, 0.0 / nNoteID - 69) * 440.0);
 		}		
 	}