Parameters

Parameters are used to allow users to customize formulas without needing to rewrite them. 

Parameters are used just like variables, with two exceptions: you cannot write to them, and you 

must prefix them with the @ character (so the compiler can determine they are parameters instead 

of variables). Here is an example that uses a parameter:

Mandelbrot {

init:

z = 

0

loop:

z = z^

@power 

+ 

#pixel

bailout:

|z| < 

4

}

The parameter used here is @power. In the Formula tab, the user can now enter a value for this 

parameter and view the Mandelbrot set of any power using just one formula.

By default, the type of a parameter is complex. You can change that by adding a 

param block

 to the 

default section of your formula and providing the necessary settings. Using the param block, you 

can also specify enumerated parameters. With enumerated parameters, the user does not have to 

enter a numerical value, but rather chooses an item from a drop down list.

It is also possible to use user functions. These can be used just like normal functions, with the 

exception that the user can choose the actual function from a list of all available functions. Here is an 

example with a user function:

Mandelbrot {

init:

z = 

0

loop:

z = 

@myfunc

(z) + 

#pixel

bailout:

|z| < 

4

}

Now, the user can use sqr, but also sin and cos and many other functions with this formula. You 

can customize the behavior of the user function using the 

func block

 in the default section.

Notes

G     

It is possible to write to parameters, although this is not recommended and can make your 

formulas run slower. It is provided for compatibility with old Fractint formulas.

G     

There are six predefined parameters: p1..p6, and four predefined functions: fn1..fn4. You do 

not need to use the @ prefix with these parameters and user functions. However, it is 

recommended to use your own names instead of these (with the @ prefix) to make your 

formulas easier to understand.

G     

The param and func blocks also provide settings for changing the caption, default, minimum 

and maximum values of parameters and user functions, as well as adding a small help text.

G     

Parameters are sorted alphabetically in the user interface, unless you provide a param block 

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