套利交易 (Arbitrage Trading)

I have been using this method manually based off this formula.
You use only GBPUSD EURGBP EURUSD

NOW. IT CAN ONLY BE A S.S.B. OR A B.B.S combination, in that order.
Lots sizes GBPUSD uses price of EURGBP, rest of the 2 are 1 lots

GBPUSD EURGBP EURUSD
ex, LOTS S 0.95 B 1 B 1

NEXT STEP IS DECIDING WHICH COMBO TO CHOOSE FROM? VERY IMPORTANT
IF SSB THEN,
SELL MARKET ORDER GBPUSD
BUY MARKET ORDER EURUSD
PLACE A PENDING ORDER SELLLIMIT ORDER EURGBP XX PIPS ABOVE CURRENT PRICE

IF BBS

BUY MARKET ORDER GBPUSD
SELL MARKET ORDER EURUSD
PLACE A PENDING ORDER BUYLIMIT ORDER EURGBP XX PIPS BELOW CURRENT PRICE

AS LONG AS THE PENDING ORDER IS TRIGGER YOUR LOCKED IN A PROFITABLE ARBRITRAGE TRADE.

I NEED A WAY TO HELP DECIDE WHICH COMBO TO CHOOSE AND IF THE PENDING ORDER IS LIKELY TO BE TRIGGERED THAT DAY. IF NOT TRIGGERED THEN YOUR IN A DEEP DRAWDOWN TILL IT RETURNS BACK, THATS WHAT I AM TRYING TO AVOID.

ANY IDEAS?