The ValueWhen function returns the value of the selected
`data array' when a defined `expression' is true on the `N'th most recent
occurrence. That is to say, it allows you to specify which data array value to
display (e.g. closing price, the RSI, another formula etc.) at the time a given
expression occurred. Furthermore, if the expression has occurred more than once,
you can also select which occurrence to use (e.g. the third most recent
SYNTAX ValueWhen(Nth, Expression, Data Array)
Nth _ Is the number of occurrences, of the `expression', you
wish to refer back when obtaining the value of the selected data array.
Expression _ The technical condition that you are going back
through the data to search for and the `N' will dictate how many occurrences you
Data Array _ On the period that `Expression' is found `N'
times ago, it is the value of this data array that is returned.
The following formula identifies the last occasion that an 8
period simple moving average crossed with a 21 period simple moving average, and
then took the closing value for that period:
In the above example:
Nth = 1
Expression = Cross(Mov(C,8,S),Mov(C,21,S))
Data Array = C
A more useful application of this example could be:
This formula identifies the last occasion that an 8 period
simple moving average crossed with a 21 period simple moving average and then
took the closing value for that period. It added 3% to that value (denoted by
`*1.03') and then searched for when the closing price closed above this new
value (denoted by the `C>').
Looking at Figure 3.22, we can see this example applied to
the chart below as an indicator.
Figure 3.2 _ Alert Indicator
Construct formulas for the following:
1. Return the value of the low on the most recent
occasion that the close was at least 2% lower than the open for the period:
2. Return the value of the close on the most recent
period that the 10 period simple moving average of the closing price crossed
above the 30 period simple moving average of the closing price:
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