2014.12.29 Rouble to dollar approximation
This is today's approximations of the price of 100 roubles, measured in the USA cents. The figure is from
http://mizugadro.mydns.jp/t/index.php/File:2014.12.29rubleDollar.png
The abscissa has sense of time, measured in days since 2014.10.27.
The light green spots represent data from
https://www.mataf.net/en/currency/converter-USD-RUB
The black straight line shows the linear approximation,
y = Linear(x) = 227.499−0.581655x
The monotonous smooth red line represent the approximation
y = Ellipse(x) = 1.16997(102.182−x)(396.475+x))
The oscillating dark green line represents the improved approximation
y = Fit(x) = Ellipse(x) + 0.959481 exp(0.0601124x) sin(0.179949(−54.6949+x))
For the Fit, the mean deviation is 3.16 (cent)
and the mean square deviation is 4.23 (cent)
In such a way, in the range -150 < x < 64, the approximation Fit provides 2 significant figures; the relative deviation from the experimental data is about one percent.
Warning: This is just fitting of experimental data. It is valid for -150 < x < 64 . You may use the extrapolation for larger values of x for your own risk.