Any way to freeze transaction cross rates in time

[noodle73]

Hi

The dynamic cross rates in Multibit are one of my favourite pieces of functionality, an instant look at what my BTC is worth in fiat. But, for transactions that have been and gone, is there any way to freeze their exchange rate at the time the transaction was made. Sending 10 bitcoins to someone now is a big deal, but it wasn't when a bitcoin was worth $10. When I look down my transaction list I see it rewriting history with every tick of the  exchange rate. I would like to freeze these historical transactions at the BTC/fiat rate applicable at the time as it is a truer represention of the size of the transaction rather than comparing everything to today's rates.

Thanks

Chris

[jim618]

Yeah I agree it would be useful.

It gets a bit complicated though as a particular  exchange rate is not just a number : it is from a particular exchange, in a particular currency, valid at a particular time. also it might be last value, midpoint or smoothed over a period of time (if so, store the time and method of smoothing).

Also once you start adding stored exchange rates people will soon ask for daily rates - to use in accounts consolidation.

This is a fair bit of work.

What I am hoping is that now that you can export the transactions an Excel whiz will basically implement a 'rate for date' look up and then open source it. That way accountant buffs can tweak the rate they use to their heart's content.

Beancounter: I have reduced our tax bill for 2013/14 by triangulating against our primary trading partner Indonesia and using an exponential moving average to take into account the rupiah's volatility, compensating of course for the extra transit time due to the prevailing wind patterns in the Malacca Straits.

[noodle73]

I bow to your knowledge. I had in mind that transaction history would just be a static line that never changed or updated. So without needing historic data, Multibit just took your prevailing exchange rate information at the time the transaction history was written and then never updated it.

[jim618]

You 'could' do that but then people would soon, quite legitimately, want to know:
What exchange was that from ?
What time was that rate valid at ? (This is not necessarily the time of the tx due to polling/ caching of the exchange data)
I swopped from USD to CAD at 11:00 so which tx are converted using which currency ?

It's unfortunately just not a simple thing an exchange rate.
To partially implement something sometimes creates more problems than it solves.

[noodle73]

Fair points - I will leave it to you. Makes me look more generous than I was with those historical small donations!

[jim618]

Thanks for your donations !

[Mike Hearn]

Once bitcoinj supports a payments abstraction, we can add FX info to that as I guess it's a common and useful request. Even just storing "the default exchange you used at the time" would work OK.

[jim618]

I think it would be pretty useful yes over the medium term.
As people use bitcoin more in their daily lifes 'doing the monthly accounts' will become a more common activity.

I worked at an accountancy software company 2000 - 2005 so have 'fond' memories of issues such as 'triangulating against the euro'.
Oh happy days. :-)

[noodle73]

Thanks for your donations !

oh go on then, send me an address and I'll send you a coffee...

[jim618]

The MultiBit donation address is :

1AhN6rPdrMuKBGFDKR1k9A8SCLYaNgXhty

Cheers!

[noodle73]

On its way to you!

[jim618]

Thanks for that !

It did actually pay for a coffee and  BLT at Pret a Mange this afternoon.

I look forward to the day places like that take bitcoin directly.

:-)