Lua Script Primer
rezonator uses Lua internally to calculate custom formulas. Here are some citations from the original documentation to get a brief intro into the language. Provided information should be sufficient to write formulas for schema parameters, custom elements or to carry out calculations in Formula Calculator.
Lua is a free-form language. It ignores spaces (including newlines) and comments between lexical elements (tokens), except as delimiters between names and keywords.
Variables
Variables are places that store values.
Lua is a case-sensitive language: and is a reserved word, but And and AND are two different, valid names.
The following keywords are reserved and cannot be used as names:
and, break, do, else, elseif, end,
false, for, function, goto, if, in,
local, nil, not, or, repeat, return,
then, true, until, while.
A numeric value can be written with an optional fractional part and an optional decimal exponent, marked by a letter e or E. Examples of valid values are 3, 3.1416, 314.16e-2, 0.31416E1, 34e1
Lua allows multiple assignments:
x, y = 10, 20
x, y, z = y, z, x
Operators
Lua supports the following arithmetic operators:
+ — addition
- — subtraction
* — multiplication
/ — float division
// — floor division
% — modulo (remainder of a division that rounds the quotient towards minus infinity)
^ — exponentiation (it works for non-integer exponents too)
- — unary minus
Lua supports the following relational operators:
== — equality
~= — inequality
< — less than
> — greater than
<= — less or equal
>= — greater or equal
Mathematical Functions
Lua provides a set of mathematical functions in the math library. One has to call them using the library name, e.g., math.sin(math.pi / 4). For convenience, rezonator supports its own set of standard mathematical functions that can be used without any additional prefix, e.g., sin(pi()/4).
sin — returns the sine of the angle in radians.
sinh — returns the hyperbolic sine of the argument.
asin — returns the arcsine of the argument as an angle in radians.
cos — returns the cosine of the angle in radians.
cosh — returns the hyperbolic cosine of the argument.
acos — returns the arccosine of the argument as an angle in radians.
tan — returns the tangent of the angle in radians.
tanh — returns the hyperbolic tangent of the argument.
atan — returns the arctangent of the argument as an angle in radians.
cot — returns the cotangent of the angle in radians.
coth — returns the hyperbolic cotangent of the argument.
acot — returns the arccotangent of the argument as an angle in radians.
sec — returns the secant of the angle in radians.
sech — returns the hyperbolic secant of the argument.
csc — returns the cosecant of the angle in radians.
csch — returns the hyperbolic cosecant of the argument.
abs — returns the absolute value of the argument.
floor — returns the largest integer that is not greater than the argument. For example, floor(41.2) = 41.
ceil — returns the smallest integer that is not less than the argument. For example, ceil(41.2) = 42.
exp — returns the value of e to the power of the argument, where e is the base of natural logarithms.
ln — returns the natural logarithm of the argument. Natural logarithm uses base e.
lg — returns the logarithm of the argument in base 10.
sqrt — returns the square root of the argument.
deg2rad — converts the angle from degrees to radians.
rad2deg — converts the angle from radians to degrees.
pi — returns value π.
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