Subgroup basis matrix: Difference between revisions

Mike Battaglia (talk | contribs)
edited over one another
Mike Battaglia (talk | contribs)
nice latex
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=Example=
=Example=
Say that our JI parent group J is in the 7-limit, and we want to look at temperaments on the 2.9/7.5/3 subgroup. We can create the subgroup mapping matrix by forming a matrix in which the columns are the monzo representation of these intervals:
Say that our JI parent group J is in the 7-limit, and we want to look at temperaments on the 2.9/7.5/3 subgroup. We can create the subgroup mapping matrix by forming a matrix in which the columns are the monzo representation of these intervals:
<math>
\newcommand{dangle}[][]{\style{display: inline-block; transform-origin: 50% 50% 0px; transform: rotate(90deg); }{ \rangle}}
\newcommand{hpipe}[][]{\style{display: inline-block; transform-origin: 50% 50% 0px; transform: rotate(90deg); }{ |}}
</math>


<math>
<math>
\left[ \begin{array}{rrr}
\left[ \begin{array}{rrr}
\hpipe & \hpipe & \hpipe\\[-20pt]
1 & 0 & 0\\
1 & 0 & 0\\
0 & 2 & -1\\
0 & 2 & -1\\
0 & 0 & 1\\
0 & 0 & 1\\
0 & -1 & 0
0 & -1 & 0\\[-20pt]
\dangle & \dangle & \dangle\\[-20pt]
\end{array} \right]
\end{array} \right]
</math>
</math>
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<math>
<math>
\left[ \begin{array}{rrr}
\left[ \begin{array}{rrr}
\hpipe & \hpipe \\[-20pt]
0 & 0\\
0 & 0\\
2 & -5\\
2 & -5\\
0 & 1\\
0 & 1\\
-1 & 2
-1 & 2\\[-20pt]
\dangle & \dangle\\[-20pt]
\end{array} \right]
\end{array} \right]
</math>
</math>
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<math>
<math>
\left[ \begin{array}{rrrrrl}
\left[ \begin{array}{rrrrrl}
12 & 19 & 28 & 34
\langle 12 & 19 & 28 & 34 |
\end{array} \right]
\end{array} \right]
</math>
</math>
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<math>
<math>
\left[ \begin{array}{rrrrl}
\left[ \begin{array}{rrrrl}
12 & 4 & 9
\langle 12 & 4 & 9 |
\end{array} \right]
\end{array} \right]
</math>
</math>
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which tells us that the restriction of the 12-EDO patent val to the 2.9/7.5/3 subgroup is the sval <12 4 9|, with a mapping of 12 steps for 2/1, a mapping of 4 steps for 9/7, and a mapping of 9 steps for 5/3.
which tells us that the restriction of the 12-EDO patent val to the 2.9/7.5/3 subgroup is the sval <12 4 9|, with a mapping of 12 steps for 2/1, a mapping of 4 steps for 9/7, and a mapping of 9 steps for 5/3.


We can also send temperament mapping matrices into the subgroup matrix. For instance, here's 7-limit [[Starling_temperaments#Sensi temperament|sensi]]:
We can also send temperament mapping matrices into the subgroup matrix. For instance, here's 7-limit [[Starling_temperaments#Sensi temperament|sensi]] - with the rows explicitly notated as vals, and the columns explicitly notated as tmonzos:


<math>
<math>
\left[ \begin{array}{rrrrrl}
\left[ \begin{array}{rrrrrl}
1 & -1 & -1 & -2\\
\: \hpipe & \hpipe & \hpipe & \hpipe \:\: \\[-20pt]
0 & 7 & 9 & 13\\
\langle \: 1 & -1 & -1 & -2 \: |\\
\langle \: 0 & 7 & 9 & 13 \: |\\[-20pt]
\: \dangle & \dangle & \dangle & \dangle \:\: \\[-20pt]
\end{array} \right]
\end{array} \right]
</math>
</math>
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<math>
<math>
\left[ \begin{array}{rrrrrl}
\left[ \begin{array}{rrrrrl}
1 & 0 & 0 \\
\: \hpipe & \hpipe & \hpipe \:\: \\[-20pt]
0 & 1 & 2 \\
\langle \: 1 & 0 & 0 \: | \\
\langle \: 0 & 1 & 2 \: | \\[-20pt]
\: \dangle & \dangle & \dangle \:\: \\[-20pt]
\end{array} \right]
\end{array} \right]
</math>
</math>