druid/docs/content/misc/math-expr.md

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This expression language supports the following operators (listed in decreasing order of precedence).

Operators	Description
!, -	Unary NOT and Minus
^	Binary power op
*, /, %	Binary multiplicative
+, -	Binary additive
<, <=, >, >=, ==, !=	Binary Comparison
&&,||	Binary Logical AND, OR

Long and double data types are supported. If a number contains a dot, it is interpreted as a double, otherwise it is interpreted as a long. That means, always add a '.' to your number if you want it intepreted as a double value.

Expressions can contain variables. Variable names may contain letters, digits, '_' and '$'. Variable names must not begin with a digit.

For logical operators, a number is true if and only if it is positive. (0 means false)

Also, the following in-built functions are supported.

name	description
sqrt	sqrt(x) would return square root of x
if	if(predicate,then,else) returns 'then' if 'predicate' evaluates to a positive number, otherwise it returns 'else'