Reference Math Functions

The Set Variable action allows you to compute a mathematical equation and store the result in a variable. The supported math syntax and functions are documented below. Math functions can also be used in Dialog Flow Scripts.

Operators

Story Machine supports most common math operators: + - / * ( )
It also supports a few more technical operators:

  • % - modulus, the remainder
  • ^ - power

Example:

3 + (5 * 2^4) - (27 / 10)

Math functions and constants

Story Machine supports the following math functions. These are in the form of name(value).

  • abs - absolute value
  • acos - arccosine
  • asin - arcsine
  • atan - arctangent
  • atan2(y,x) - computes the angle between the x axis and a line from the origin passing through (x, y)
  • ceil - round up to the nearest whole number
  • cos - cosine
  • cosh - hyperbolic cosine
  • exp - exponential value (e ^ x)
  • fac - factorial
  • floor - round down to the nearest whole number
  • ln - natural log
  • log - base 10 log
  • ncr - combination (n, r)
  • npr - permutation (n, r)
  • pow - power (x ^ y)
  • sign - sign, 1 or -1
  • sin - sine
  • sinh - hyperbolic sine
  • sqrt - square root
  • tan - tangent
  • tanh - hyperbolic tangent

Story Machine also provides the following math constants, which can be used in equations.

  • e - Euler’s number
  • pi - Pi
  • deg2rad - multiply with an angle in degrees to get radians
  • rad2deg - multiply with an angle in radians to get degrees
  • random - a random number between 0 and 1

Logical functions

  • approach(value, target, change) - moves value towards target at rate change. Will not surpass target.
  • distance(x1, y1, x2, y2) - returns the distance between (x1, y1) and (x2, y2)
  • distance2(x1, y1, x2, y2) - same as distance(), but returns the squared distance
  • clamp(value, min, max) - clamps value to the min…max range
  • loop(value, min, max) - loops the value along the min…max range (e.g. loop(1.2, 0, 1) = 0.2.
  • min(a, b) - returns a or b, whichever is smaller
  • max(a, b) - returns a or b, whichever is larger

Easing

  • lerp(start, end, percent) - linear interpolation between start and end
  • easeIn(start, end, percent) - ease in curve between start and end
  • easeOut(start, end, percent) - ease out curve between start and end
  • easeInOut(start, end, percent) - ease in and out curve between start and end

Variables

You can use variables in place of any value in Story Machine. Variables may have spaces in their names, and are not case-sensitive. Note however that variable names must be unique, and spaces/case are not differentiating. Therefore “my Value X” is the same variable name as “myvaluex”.