# Talk:Parabolic SAR

Article is generally understandable. I think it needs more references. This is an advanced topic that may not be understandable to those who are not involved in technical analysis of commodities or stocks.

GT Comment begins here...

The mathematics is extremely sloppy.

If alpha is a time-varying parameter with bounds, it ought to be expressed as such - not displayed as if it is a parameter. According to the text, $\alpha\!$ starts at 0.02 and rises at a rate of 0.02 per iteration.

So in fact the appropriate formula is

$SAR_{n+1} = SAR_n + \alpha_n( EP - SAR_n ) \!$

where

$\alpha_n=max(0.2, 0.02(n+1)) \!$

If the seed value, maximum value and time-adjustment for $\alpha\!$ can be user-defined, then the true (non-time-varying) parameters are, say, σ,τ and μ, and

$\alpha_n= max(\mu, \sigma + n \tau) \!$

It is annoying when people write variables as parameters.

77.206.39.149 (talk) 15:25, 15 August 2008 (UTC) Geoffrey Transom, France Hello, I have a non trading background and I find the following phrase confusing "today's or yesterday's price range". This is mainly because "price range" in not define anywhere. Cheers Mrphonon (talk) 16:21, 19 February 2009 (UTC)

Prices range between the highest high and the lowest low, during a time period.

-oo0(GoldTrader)0oo- (talk) 16:15, 22 February 2009 (UTC)

Gbwi Comment begins here...

Some of the formulae by GT (above) are not entirely correct.

Since 0.2 is the maximum, the function in the formula should be MIN, not MAX, like this:

$\alpha_n=min(0.2, 0.02(n+1)) \!$
$\alpha_n= min(\mu, \sigma + n \tau) \!$

--Gbwi (talk) 09:15, 26 June 2009 (UTC)

Note that n is incremented only when a new EP (extreme point) is recorded.

--Gbwi (talk) 10:33, 16 July 2009 (UTC)

## "recursively calculated"

Since "calculated" means a process, let us speak the truth and say that it is an iterative one.--VKokielov (talk) 16:10, 16 December 2010 (UTC)

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