Metallic MOS: Difference between revisions

Cmloegcmluin (talk | contribs)
Cmloegcmluin (talk | contribs)
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=== Why they cycle ===
=== Why they cycle ===


That is true of scale iterations where L - s > s. For the other type of scale iteration, where L - s < s, the result is simply reciprocated:
That is true of scale iterations where <span><math>L - s > s</math></span>. For the other type of scale iteration, where <span><math>L - s < s</math></span>, the result is simply reciprocated:


<math>\qquad L’:s’ = s:(L - s) = 1:(L - 1) = 1 / (L - 1)
<math>
\begin{align}
L’{:}s’ &= s{:}(L - s) \\
&= 1{:}(L - 1) \\
&= \frac{1}{L - 1}
\end{align}
</math>
</math>


This alone would not suffice to explain how the <span><math>L{:}s</math></span> sequences lock into a cycle of isotopes. But here’s where the magic of the metallic means comes into play. <span><math>φ</math></span> has the property that
This alone would not suffice to explain how the <span><math>L{:}s</math></span> sequences lock into a cycle of isotopes. But here’s where the magic of the metallic means comes into play. <span><math>φ</math></span> has the property that


<math>\qquad  φ - 1 = 1 / φ
<math>\qquad  φ - 1 = \frac{1}{φ}
</math>
</math>


So, in the case of <span><math>φ</math></span>:
So, in the case of <span><math>φ</math></span>:


<math>\qquad  L’:s’ = 1 / (L - 1) = 1 / (φ - 1) = 1 / (1 / φ) = φ
<math>
\begin{align}
L’{:}s’ &= \frac{1}{L - 1} \\
&= \frac{1}{φ - 1} \\
&= \frac{1}{\frac{1}{φ}} \\
&= φ
\end{align}
</math>
</math>


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A similar case is true for the silver mean, except we have to subtract 1 from it twice before the resulting value’s reciprocal is equal to the silver mean.
A similar case is true for the silver mean, except we have to subtract 1 from it twice before the resulting value’s reciprocal is equal to the silver mean.


<math>\qquad  δ_s - 1 - 1 = 1 / δ_s
<math>\qquad  δ_s - 1 - 1 = \frac{1}{δ_s}
</math>
</math>


And for the bronze ratio, we must subtract thrice:
And for the bronze ratio, we must subtract thrice:


<math>\qquad  δ_s - 1 - 1 - 1 = 1 / δ_s
<math>\qquad  δ_b - 1 - 1 - 1 = \frac{1}{δ_b}
</math>
</math>