File:2014.12.29fitA300.png

Price of 100 Russian roubles measured in the USA cents.

Abscissa is time, measured in days since the date 2014.10.27, that dorresponds to the beginning of the project,

The green dots correspond to the data by https://www.mataf.net/en/currency/converter-USD-RUB

The red monotonous line shows the approximation

$y=f_3(x)=1.11631 \sqrt{(106.006 - x) (419.029 + x)}$

the blue oscillating curve shows the approximation

$\displaystyle y=f_3(x)+6.3 \exp(0.028 x) \sin\big(\frac{\pi}{16} (-54 + x)\big)$

Both approximations are made 2014.12.29. They approximate the experimental data for the range $-150<x<160$.

it will be interesting to see, how far will these functions approximate the experimental data for x>160.