#restraints

npm install restraints

var restraints = require('restraints')
   , converter = restraints('9 * c = 5 * (f - 32)')
//when either the value for 'c' or 'f' are updated, their value will be attached to converter

converter({c : 21})
converter.f === 69.8
converter('forget') //all values are forgotten
converter({f : 80})
converter.c === 26.66666

restraints is useful for creating a set of mathematical equations:

var equation = restraints('x^y = z')
equation({x:10, y:2})
equation.z === 100 //10^2=100

equation('forget') //all values are forgetten

equation({x:2, z:8})
equation.y === 3 //2^3=8

var f = restraints('x = y = z')
f({x:10})
assert(f.y === 10)
assert(f.z === 10)

var f = restraints('x = y^2 = z^3')
f({y : 10})
assert(f.x === Math.pow(f.y, 2))
assert(f.z === Math.pow(f.y, 2/3))
assert(f.z === Math.pow(f.x, 1/3))