Navigating the PCF Functions, Parameters, and Constants Menu
This menu is available from anywhere you would edit either a indicator or Condition (boolean) formula. In this example we are using the Indicator (PCF) Formula from the New Menu. This article will walk you through the functionality of each of the menu items and conclude with an example of these items in use. Please refer to the help articles on Constants, Parameters and Functions for more specific details on each of those items.
Click on the hamburger button to open the menu.
This opens a menu which allows you to choose from several items to add to your formula
Click on Add parameter and this dialog box will appear
This dialog allows you to name your parameter, assign it a default value, and add a tagged description of what that parameter does, in this example we will name it "Period" give it a value of "20" and set the description to "Defines number of bars in period"
Select OK to add it to the PCF editor window
This is how a parameter will appear in the editor window
Please note that Parameters must always be entered above the formula, you can also type in the parameter using the above syntax instead of adding it using the menu button.
Selecting Add Constant will make this dialog appear
This dialog allows you to name your constant, assign it a default value, and add a tagged description of what that constant does, in this example we will name it "OHLC" give it a value of "C" and set the description to "Defines part of bar used, can be O,H,L or C"
Select OK to add it to the PCF editor window
This is how a constant will appear in the editor window
Please note that Constants must always be entered above the formula, you can also type in the constant using the above syntax instead of adding it using the menu button.
Click on Add New Function and a new PCF editor window will appear
The <desc> and <tag> comment lines allow you to add a description of what your function does and ad searchable tags to your function. In this example we will name the function "MaxHigh" add "Returns the maximum High value of the last 20 bars" to the description and "20 Highs" to the tag line. We will enter in the formula: MAXH20
We are going to save this formula for later use by clicking on the hamburger button and selecting Save formula
You can name the formula whatever you like but for continuity we are going to save it as MaxHigh20, once named click the save button
Once you have (optionally) saved the formula click OK to add it to your formula window
The function has now been added to the formula window
Selecting Add Function from Library... will open the formula library
In this example we will load the previously saved formula MaxHigh20, please note that searching for the formula name MaxHigh20 or the tag that we assigned to it "20 Highs" will return it in the results
Select the formula from the results
This will open that formula in an editor window, select OK to add it to your main formula
The function is now available for use
Selecting Edit in standalone window pops out a larger formula editor window with the same functionality as the standard editor.
We will now show how to call the function, parameter and constant in an example formula that describes where the current price "C" is relative to the maximum high and minimum low of the last 20 bars and creates and average of that value. Please note that the purpose of this formula is to show how these items can be utilized and should not be considered a recommended indicator in any way. The formula we will be creating is:
AVG(((MAXH20) - C) / (C - MINL20), 20)
First add the function Avg to the formula followed by two opening parentheses
Note that as you type the code completion gives you a list of available functions and declarations as well as a description of that function. You can use the up and down arrows to move through the list of functions, pressing enter will select the highlighted function.
Next we will call the MaxHigh function
User Functions, Parameters, and Constants all begin with the pound sign "#"
Note the description for this function is what was entered between the <desc> tags previously
Now we will add a minus sign and call our OHLC constant then add a closing parentheses
Note the description of the constant matches what is placed between the <desc> tags to the right of the defined constant
Next we will add a division sign and subtract the 20 period minimum low from our OHLC constant
MINL20 could have been saved as it's own user defined function, it was entered this way to show the use of user defined functions and system functions.
Finally we will call our period parameter to define the period of the average and add the final closing parentheses to complete the formula
Note the description of the parameter matches what is placed between the <desc> tags to the right of the defined parameter
You can view the flattened formula (once there are no formula errors) by clicking the blue magnifying glass icon
This shows that our Parameter, Constant and function were all passed through correctly
We can change our Parameter value to 50 and Constant value to O in the heading and see how they change the formula
