The "Check" menu command appears to actually run the script to find out how many future (and past) bars are needed. So if your script works differently under different conditions, be aware that you may miss some of the crystal balling it does.
The "Check" command does seem to get confused by some spurious operations that actually are not looking into the future, as far as I could see. I don't run it frequently now, since I know my code well enough to know exactly what it is doing now. But when I was running it, I would occasionally get warnings that made no sense. (Sorry, can't remember the details now.) Why not provide an automatic check for this? I think it should. There should be an option to turn it OFF, but it should be ON by default. Ideally the option should be setable in each script. New scripters need this option especially because it is difficult to tell what AB scripts are doing until you no longer need this aid, and even then, it is easy to make a sign error on a Ref call. Having said that, I now realize that there are a few situations in which it is valuable to be able to look into the future, or equivalently, to modify the past. There are two cases I can think of: 1. Indicators. For example, my Giant Candlesticks script must wait for an entire bar to be finished before it can draw any of it. Many trend line plots (e.g. zigzag) use future data to determine how best to plot the trend. 2. Training: For example, a system that learns patterns in a stock or market by looking at ALL the available data, and then uses that learning to set parameters for backtesting. I experimented with a candlestick pattern system that does this. You have to be very careful with such a system, however, so that you are not merely fullfilling your own prophecy. dan On Sunday 18 June 2006 04:46 am, Lester Vanhoff wrote: > I don't know if this can be somehow done automatically but each formula can > be tested manually if it looks into the future. See the screenshot here: > > http://img227.imageshack.us/img227/8584/checkfuture5nd.png > > Lester > > --- In [email protected], "Chris" <[EMAIL PROTECTED]> wrote: > > If I have a trading system such as this: > > > > Buy = Cross( Close , EMA(Close, 10) ); > > Sell = Cross( EMA(Close, 10) , Close ); > > > > and my buy and sell price settings are set to "Open" with Buy Delay = > > 0, I have an untradeable system because the closing prices are not > > known until after the trade has executed (open). If backtested, AB will > > give unrealistic returns because the system is allowed to peek into the > > future (knowing the closing prices at the open). Shouldn't AB detect > > this sort of situation and flag the user? Would this be a worthwhile > > feature request? > > > Please note that this group is for discussion between users only. > > To get support from AmiBroker please send an e-mail directly to > SUPPORT {at} amibroker.com > > For other support material please check also: > http://www.amibroker.com/support.html > > > Yahoo! Groups Links > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> Something is new at Yahoo! Groups. Check out the enhanced email design. http://us.click.yahoo.com/rlNZQC/gOaOAA/cosFAA/GHeqlB/TM --------------------------------------------------------------------~-> Please note that this group is for discussion between users only. To get support from AmiBroker please send an e-mail directly to SUPPORT {at} amibroker.com For other support material please check also: http://www.amibroker.com/support.html Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/amibroker/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
