appharm.en.sgml
brancharpeges
changeset 0 1397c2bfefa2
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/appharm.en.sgml	Mon Dec 26 19:21:22 2005 -0500
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+<?xml version="1.0"?>
+<!DOCTYPE appendix PUBLIC "-//OASIS//DTD DocBook XML V4//EN"
+        "/usr/share/sgml/docbook/dtd/xml/4.2/docbookx.dtd"
+[
+  <!ENTITY % struct-dtd SYSTEM "struct.dtd">
+  %struct-dtd;
+]>
+<appendix id="aharmonies" revision="$Revision: 1841 $ $Name$" userlevel="adv"
+  vendor="1.12" xmlns:xi="http://www.w3.org/2003/XInclude">
+  <title id="atharmonies">The harmonic principle</title>
+    
+  <para>The Harmonies Attributes came from a principle known from
+    Antiquity and named harmonics.  Harmonics are used in music as
+    what we known as scales.  A scale contains twelve notes (when we
+    count the black notes on piano keys) which repeat infinitely.
+    Between one note and the next one with the same name, there is a
+    difference of pitch (the frequency of the notes) which is exactly
+    the double.</para>
+
+  <para>In the Harmonies, the recipe is the same except that we only
+    kept ten notes and that the value is multiply by 10 at each
+    repetition.  This scale is called the logarithmic decimal scale
+    and <xref linkend="tmesures"/> only gives you an approximation of
+    it.</para>
+
+  <para>The important values to remember in this scale are those
+    associated with the value 0, 3, 5 and 10, which are 1, 2, 3 and 10
+    respectively.  From those ones, you can find back the full table
+    simply by adding and subtracting the empty spaces from the known
+    values, and then to replace additions with multiplications, and
+    subtraction with divisions.  For example, to get back the value of
+    2, we can observe that 5-3=2, so, once the substitution done, we
+    have 3/2=1.5.</para>
+
+  <para>Note that those numbers are only approximation except for 0
+    (which equal exactly 1) and 10 (which equal exactly 10).  A 3
+    points difference is equivalent to a factor of 2.01, and a 5
+    points difference is equivalent to approximately 3.2.</para>
+
+</appendix>
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