The P variable is a special data array identifier that can be
used to reference any indicator or price plot. Although it's called the `P'
variable it doesn't work like a variable. It works similarly to other data array
identifiers, the only difference being it's more versatile. The reason it's
called a variable is because it can be changed depending on which indicator or
price plot it's referencing. To select an indicator or price plot, click once on
the item and small squares appear evenly spaced along the item. When selected we
can now use this information by referencing the P variable. The syntax is simply
`P'. Thus, by simply typing `P' in a formula, in place of other data array
identifiers, we can reference our selected information. (e.g., `HHV(P,20)' and
The following example was taken from MetaStock's help file:
The following custom indicator plots an "MACD-type" indicator
(i.e., the difference between a 12 period and a 26 period exponential moving
average) of the plot it is dropped on.
Mov( P, 12, E) - Mov( P, 26, E)
If you plot the predefined Relative Strength Index (RSI)
indicator and then drop the above custom indicator on it from the QuickList, the
result will be an MACD of the Relative Strength Index (RSI) indicator.
Of course, you could write the preceding formula without
using the "P" identifier as shown below, but you would have to modify it if you
wanted an MACD of an indicator other than the Relative Strength Index (RSI).
Mov( RSI(C,20), 12, E) - Mov(RSI(C,20), 26, E)
Although there are numerous uses for the P variable, perhaps
its most functional use is within an exploration. By using the P variable it
becomes possible to compare securities against a selected base security. This
concept forms the basis of our Relative Strength Comparison (RSC) explorer.
Later, in The Explorer chapter, we'll examine this in depth (Refer to page 154).
That said, here's a bit of a teaser. Basically the P variable
represents a pre-selected price plot that is chosen before the exploration is
run. Then wherever we've made reference to the P variable, MetaStock will
reference this selected price plot. In that way, we can use a base security by
which to compare other charts. For example, we can compare market sectors
against a chosen market index. We can then rank these sectors to find out which
ones are performing the strongest; and from there we can identify which shares
fall within these sectors.
That's the power behind the P variable and now that we've
whet your appetite, we'll say no more until The Explorer chapter.
article is a snippet from the
MetaStock Programming Study Guide...
The Simple Secret to Make Metastock Easy & Identify Profitable
copyright 2007 www.meta-formula.com