# Constants Statement # Constants Statement Syntax

The Fractal Science Kit fractal generator constants statement is 1 of the statements used in the section of the program instructions to define the program's Properties.

The constants statement is used to define a set of complex constants available to the program instructions. The format of the constants statement is:

constants [ <Name> ] {
<Identifier> = <Expression>
<Identifier> = <Expression>
...
}

<Name> and each <Identifier> must be a valid identifier. Each <Expression> must be a valid complex expression. The <Expression>  may use any of the defined options or enums. OptionArray statements may reference these constants.  Option definitions may not use these constants in their enabled expressions, however. Finally, the <Expression> must evaluate to a complex (non-object) value.

The name of the constant is <Name> followed by a period (.) and then the <Identifier>. <Name> is optional when you define the set of constants, and if it is not given, the name of each constant is simply the <Identifier>.

Example:

option Angle {
type = Float
caption = "Angle"
details = "Angle of rotation"
default = 0
range = [-360,360]
}
constants {
}

This example defines a complex constant named Rotation that can be used to rotate a number. Remember that the value of the expression z*Cis(A) is equal to the point z rotated about the origin by A radians if A is a floating point number. Using this fact and the above definitions, we can rotate a point z by Angle degrees about the origin using the expression z*Rotation.

Example:

constants Math {
TwoPI = 2 * Math.PI
Cos0  = 1
Cos30 = Sqrt(3)/2
Cos45 = Sqrt(2)/2
Cos60 = 0.5
Cos90 = 0
Sin0  = 0
Sin30 = 0.5
Sin45 = Sqrt(2)/2
Sin60 = Sqrt(3)/2
Sin90 = 1
}

This example creates several math related constants. These are accessed in your code as Math.TwoPI, Math.Cos0, etc.