Pre-programmed functions

In addition to the mathematical operators, MetaStock ships with over 200 pre-programmed functions to give your coding versatility. The bulk of these fall into three categories: analysis tools, indicators and candlesticks. Over the coming lessons we will look at the more commonly used functions, with explanations and applications for each.

Functions and parameters

Before we begin, we must explain what function parameters are and where they are used. A function is a set of predefined mathematical operations that MetaStock follows; a parameter provides a function with the information it needs to calculate those operations. Some functions need no parameters; others need several.

Let's look at a couple of examples.

ATR(14)

This formula calculates a 14-period Average True Range. The only parameter required is the number of periods, 14. The ATR syntax is ATR(Periods), and we put it to work in the Average True Range tutorial.

Mov(C,7,S)

This formula plots a 7-period simple moving average. The parameters are the data array (C), the periods (7) and the moving average type constant (S). Notice that when a function has multiple parameters, each parameter is separated by commas. The moving average syntax is Mov(Data Array, Periods, Constant), and it appears again and again through the rest of the course.

The universal parameters

That last example introduces the idea that there are different types of parameters. Some are specific to a particular function; others are near universal. The two most universal are the price data array, which you already know from Lesson 1, and the periods parameter.

Periods refers to a single value, a numeric constant, that determines the time period of a function. The periods parameter is the 7 in Mov(C,7,S): it makes the moving average a seven-period average. The less common parameters will be explained as they arise in their respective functions.

Next lesson

With 200-plus functions available, the real power comes from combining them. In Lesson 5 we learn to nest one function inside another, and meet the Alert function.