Chord complexity: Difference between revisions

Line 211: Line 211:
<math>\displaystyle D_s(a, b) = \frac{(ab)^{s/2}}{(a/b)^{s/2} + (b/a)^{s/2}}</math>
<math>\displaystyle D_s(a, b) = \frac{(ab)^{s/2}}{(a/b)^{s/2} + (b/a)^{s/2}}</math>


That denominator can be rewritten in terms of the <math>\cosh</math> function as follows:
By using the hyperbolic trigonometric identity <math>\cosh x = (e^x + e^{-x})/2</math>, that denominator can be rewritten in terms of the <math>\cosh</math> function as follows:


<math>\displaystyle (a/b)^{s/2} + (b/a)^{s/2} = 2 \cosh(s/2 \log(b/a))</math>
<math>\displaystyle (a/b)^{s/2} + (b/a)^{s/2} = 2 \cosh(s/2 \log(b/a))</math>