This is a re-implementation of Moon Math that runs locally as a CLI program. It's written in Go using the Bubble Tea library, and uses Coindesk to source price data.

"Theory"

Given a pair of quotes taken at the start and end of some period,

(t_s, p_s), (t_e, p_e)

we can derive the total gain for that period, and its length in days.

g = p_e / p_s d = t_e - t_s

Combining these, we can calculate the compounding daily periodic rate (CDPR).

r = g^{1/d}

We can use this rate to project the price p_f at some x days in the future.

p_f = p_e r^x

If we instead make p_f a target price, we can solve this equation for x, telling us how many days it will take to reach that target.

x = {{log(p_f) - log(p_e)} \over log(r)}

Future Improvements

Support other assets available from Coindesk.
Configurable projection milestones.
Allow projection by date, e.g. use the CDPR to calculate what the price would be on a particular date.
Log errors to a file.