Delta-rational chord: Difference between revisions

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}} is taken to be the DR chord that is being approximated.
}} is taken to be the DR chord that is being approximated.


Rewriting a bit, if 1:''r''<sub>1</sub>:''r''<sub>2</sub>:...:''r''<sub>''n''</sub> has delta signature {{nowrap|+ε<sub>1</sub> +ε<sub>2</sub> ... +ε<sub>''n''</sub>}} (where the chord is written to start on 1, i.e. 1:{{nowrap|1 + ε<sub>1</sub>}}:...), let <math>D_i = \sum_{k=1}^i \delta_i</math> (the ''target'' delta signature) and <math>E_i = \sum_{k=1}^i \epsilon_i</math> (the ''approximating'' delta signature). Then the resulting linear least-squares optimization problem is
Rewriting a bit, if 1:''r''<sub>1</sub>:''r''<sub>2</sub>:...:''r''<sub>''n''</sub> has delta signature {{nowrap|+ε<sub>1</sub> +ε<sub>2</sub> ... +ε<sub>''n''</sub>}} (where the chord is written to start on 1, i.e. 1:{{nowrap|1 + ε<sub>1</sub>}}:...), let <math>D_i = \sum_{k=1}^i \delta_i</math> (the ''target'' delta signature) and <math>E_i = \sum_{k=1}^i \epsilon_i</math> (the ''approximating'' delta signature). Then (after some computation) the resulting linear least-squares optimization problem is


<math>
<math>
  \displaystyle{ \underset{x}{\text{minimize}}  \sqrt{\sum_{i=1}^n \Bigg( D_ix - E_i \Bigg)^2 } }
  \displaystyle{ \underset{x}{\text{minimize}}  \sqrt{\sum_{i=1}^n \Bigg( D_i - E_ix \Bigg)^2 } }
</math>
</math>


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<math>
<math>
x = \displaystyle{\frac{\sum_{i=1}^n D_i E_i}{\sum_{i=1}^n D_i^2},}
x = \displaystyle{\frac{\sum_{i=1}^n D_i E_i}{\sum_{i=1}^n E_i^2},}
</math>
</math>