Equation.js/README.md

Equation

Solve math expressions or create equations for repeated and complex Math tasks.

To use in browser, download equation.min.js.

// solve
console.log(Equation.solve('4 * lg(4) ^ 3')); // 32

// equation
let sphereArea = Equation.equation('4 * PI * r^2');

console.log(sphereArea(5)); // 314.1592653589793

You can also register your own operators and constants.

// these options are explained below
Equation.registerOperator('$', {
  fn: a => 1/a,
  format: '10',
  precedence: 2
});

Equation.solve('$2'); // 0.5
Equation.solve('$5'); // 0.2

Equation.registerConstant('N', () => {
  return Math.random() * 10 + 10
});

Equation.solve('N'); // a number between 10 and 20

API

####solve(expression: String) Takes a math expression and evaluates it, returning the result.

###equation(expression: String) Takes a math expression containing variables, returning a function which replaces the variables with given arguments, and solves the expression.

###registerOperator(key: String, options: Object) Registers a new operator.

Options:

#####fn The function which runs on arguments #####format The format which specifies how arguments are placed relative to operator, this is a string in which 1 indicates operator and zeroes indicate arguments.

For example + has the format 010 and factorial has 01. #####precedence Specifies the precedence of operator. The less the value, the higher the precedence, resulting in soon execution.

###registerConstant(key: String, value: Function/Number) Registers a new constant. value can be a function (takes no arguments), or a constant number.

That's right, we have named these constants but they actually can change, that's why we can use functions to define them. An example is the RAND constant which calls Math.random. TODO

• Equation solver
• More tests