Re: [amibroker] SetBarsRequired()...?

[Doji <dojistarbullish@xxxxxxxxx>]

Title: AFL Function Reference - SETBARSREQUIRED

SETBARSREQUIRED - set number of previous and future bars needed for script/DLL to properly execute

Miscellaneous functions (AFL 2.1)

SYNTAX	setbarsrequired( backwardref = -1, forwardref = -1 )
RETURNS	nothing
FUNCTION	set number of previous and future bars needed for script/DLL to properly execute. If your formula is pure AFL you don't need to use this function at all, as AmiBroker automatically calculates number of bars required for all its built-in functions. But if you are using script or a DLL you may need to use this function to make sure that your indicators are properly calculated in QuickAFL mode. Specifying -1 means no change. For example if you are using the script that calculates 100 bar moving average you may need to call SetBarsRequired( 100, 0 ); at the very beginning of your formula. Please note that in most cases it is not necessary (even if you are using script or DLL) because AmiBroker always provides at least 30 past data bars more than needed.
EXAMPLE	setbarsrequired( 100000, 100000 ) // require all past and all future bars
SEE ALSO

References:

The SETBARSREQUIRED function is used in the following formulas in AFL on-line library:

• Adaptive Laguerre Filter, from John Ehlers
• AFL Example
• AFL Example - Enhanced
• Andrews Pitchfork
• Andrews PitchforkV3.3
• AR_Prediction.afl
• Bullish Percent Index 2 files combined
• Bullish Percent Index 2004
• Darvas Box
• DateNum_DateStr
• Ehlers Center of Gravity Oscillator
• Ehlers CyberCycle
• Ehlers Dominant Cycle Period
• Ehlers Fisher Transform
• Ehlers Instantaneous Trend
• Ehlers Laguerre RSI
• Kagi Chart
• Modified Darvas Box
• Monthly bar chart
• Multiple sinus noised
• P&F Chart - High/Low prices Sept2003
• P&F chart with range box sizes
• PF Chart - Close - April 2004
• Prashanth
• Random Walk
• Renko Chart
• Schiff Lines
• Sine Wave Indicator
• Square of Nine Roadmap Charts
• Three Line Break - TLB
• tomy_frenchy
• Triangle exploration using P&F Chart
• Triangular Moving Average new
• Trigonometric Fit - TrigFit with AR for cos / sin
• Volatility System

More information:

Updated on-line reference

 

sidhartha70 wrote:

Hi All,

I'm a little confused about the use of SetBarsRquired()... How do I
know specifically when I need to use it...? And How do I know how many
bars to specify IF I do need to use it...??

Also, doesn't it really very significantly slow code execution
down...? From my experimentation, it seems to.

I currently have some indicators plotting (e.g. fast and slow lines
crossing) and the exact bar on which a cross occurs seems to move as I
scroll backwards and forwards along a chart....

Any ideas...?

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