Expression#
A mathematical expression that may use various mathematical operators, variables / constants, and functions, and returns a floating point number when evaluated.
Expressions are defined as strings and evaluated by Paralithic.
Expressions are written using simple mathematical syntax, for example the expression 3 + 2 / 8
, which would represent 3
plus the division of
2
by 8
.
Number Syntax#
Numbers are always handled as floating point numbers.
A number by itself is a valid expression.
Numbers can be defined simply like
5832
.Decimals are written as a whole number, a
.
, then the decimal fraction. For example64.34
.Trailing zeroes after the decimal point are permitted:
64.00
.Underscores can be used to create a visual separator (and are ignored in numbers), for example to separate each hundreds place:
1_000_000
.A quantifier letter can be added after a number to specify its quanity, for example
2m
is equivalent to2 * 1000
or2000
, wherem
refers to the metric prefix ‘mega’.
Quantifier 
Value 
Name 
n 
0.000 000 001 

u 
0.000 001 

m 
0.001 

K 
1_000 

M 
1_000_000 

G 
1_000_000_000 
Numbers can be prefixed with a
+
or
to indicate whether they’re positive or negative. For example1337
and+1337
.Numbers can use scientific notation, where the character
e
(orE
) separates the significand from the exponent. For example6.72e9
is equivalent to6.72 * 10^9
or6_720_000_000
.
Variables#
Named constants / variables are numbers that are identified by a name. They can be referenced by simply stating their name, for
example to reference myVariable
in an expression: myVariable * 20
.
There is no way to define new variables within an expression. Variables are made available external from the expression.
What variables are available will depend on the context of the expression, some config
objects have certain variables like x
and y
that change based on world position, some allow you to define your own named constants for use
inside the expression.
Builtin constants#
The following constants are available to use in all expressions:
Operators#
Boolean Representation#
Expressions only work with floating point numbers, but they also support various operators that involve
boolean math. To support such operators, ‘false’ is represented as the value 0
, and ‘true’
is represented as any value that is not 0
. If an operator returns ‘true’ then that means
it will return the value 1
.
Note
Boolean values are almost always used with the if
builtin function, so
in many cases the numerical boolean representation will be invisible. For example the expression
if(1 > 2, 5, 8)
has no explicit reference to exact values 1
and 0
(i.e. true and false).
Available Operators#
The following is a list of operations available in expressions, grouped from highest precedence to lowest, where higher precedence
operators are evaluated first. Words expr
, left
, and right
are used to indicate a subexpression (which could be a
number, a variable, another operator, etc..):
Precedence 
Syntax 
Description 
1 

Grouping of expr, allows for controlling precedence 
1 

Absolute value of expr 
 

2 

Negate expr / make expr negative 
 

3 

Exponentiation, left to the power of right 
 

4 

Multiply left and right 
4 

Divide left by right 
4 

Left modulo right 
 

5 

Add left and right 
5 

Subtract right from left 
 

6 

True if left is greater than right, otherwise false 
6 

True if left is less than or equal right, otherwise false 
6 

True left is greater than right, otherwise false 
6 

True left is greater than or equal to right, otherwise false 
6 

True left is equal to right, otherwise false 
6 

True left is not not equal to right, otherwise false 
 

7 

True if left and right are true, otherwise false 
7 

True if left or right are true, otherwise false 
Associativity#
Binary operators (i.e. operators that take two arguments) are left associative, meaning given
a sequence of operators with the same precedence like so 3  2 + 1 + 3
, they will be evaluated
from left to right like so: (((3  2) + 1) + 3)
.
Functions#
Functions are called by writing the function name, proceeded by a pair of parenthesis which
contain any arguments. Successive arguments are separated by a comma ,
.
No arguments:
exampleFunction()
One argument:
exampleFunction(3)
Several arguments:
exampleFunction(3, 2)
Function arguments are expressions, for example:
exampleFunction(3 + 2 / exampleFunction(9 * 5))
Builtin Functions#
The following is a list of builtin functions available in all expressions:
Function Name 
Arguments 
Description 

1 
Rounds the argument up to the nearest integer. 

1 
Rounds the argument down to the nearest integer. 

1 
Rounds the argument to the nearest integer. 

2 
Returns the value of the first argument raised to the power of the second argument. 

2 
Returns the smallest of the two arguments. 

2 
Returns the largest of the two arguments. 

1 
Square root of the argument. 

1 
Trigonometric sine of the argument. 

1 
Trigonometric cosine of the argument. 

1 
Trigonometric tangent of the argument. 

1 
Hyperbolic sine of the argument. 

1 
Hyperbolic cosine of the argument. 

1 
Hyperbolic tangent of the argument. 

1 
Arc sine of the argument. 

1 
Arc cosine of the argument. 

2 
Arc tangent of the argument. 

2 
See the Wikipedia page. 

1 
Converts the argument (interpreted as degrees) to radians. 

1 
Converts the argument (interpreted as radians) to degrees. 

1 
Returns the absolute value of the argument. (Makes any negative numbers positive.) 

1 
Returns the base 10 logarithm of the argument. 

1 
Returns the natural logarithm (log base e) of the argument. 

1 
Returns e raised to the power of the argument. 

1 
Returns 

2 
A sigmoid function. Equivalent to 

3 
Ternary  If the first argument is true(?), then return the second argument, otherwise return the third. 
White Space#
White space characters (spaces, newlines, tabs) are permitted in expressions. Whitespace can be used to separate parts of an expression, for example to split it into multiple lines, and or add space between operators to aid readability. Any sequence of white space is equivalent.
For example splitting a function’s arguments into multiple lines:
atan2(
1 + 45,
4 / 8
)
Note
When defining multiline expressions in YAML, it is recommended to use the block style syntax
indicated by the 
character after the :
to indicate the string is mutliline, for example:
expression: 
atan2(
1 + 45,
4 / 8
)
Uses#
Used by 3 parameters:
In EXPRESSION_NORMALIZER in NoiseSampler:
expression Expression  An expression utilizes the
in
variable (short for ‘input’).
Comments#
Any text after and including the sequence
//
on the same line is a comment. Comments are ignored.For example:
4 * 2 // This is a comment
Multiline comments are also supported, text between the
/*
and*/
delimiters is treated as a comment and is ignored.For example: