I just discovered something we should all be aware of. The values of numeric operations in MT4 can vary between different machines! This is a serious problem, since all EAs depend on the numeric precision of calculations.

The discovery came when I was moving my live account trading from my Windows XP machine to a VPS on the Amazon Cloud. Under the XP machine, a Dell Latitude laptop, RSI is displaying a value approximately 3.0 increments greater than on the VPS when placed on the same currency pair. The Tick Chart between the 2 environments is tracking identically and the versions of MT4, etc., are likewise identical. The evidence suggests that there may be some underlying issue with the C compiler used to build MT4 and how it optimizes floating point operations on different hardware.

I will continue to monitor the situation to determine what effect this discrepancy will have on the EA function. As some people complain of not getting the same results with the same EAs on the same brokers with the same set files, there is the possibility that the computing platform is the reason.

I will update the forum with my results.