# Import

The library can easily be extended with functions and variables using the
`import` function. The function `import` accepts a filename or an object with
functions and variables.

Function `import` has the following syntax:

```js
    math.import(object: Object [, options: Object])
    math.import(moduleName: String [, options: Object])
```

The first argument can be a module name or an object. The optional second
argument can be an object with options. The following options are available:

- `{Boolean} override`
  If true, existing functions will be overwritten. False by default.
- `{Boolean} wrap`
  If true (default), the functions will be wrapped in a wrapper function which
  converts data types like Matrix to primitive data types like Array.
  The wrapper is needed when extending math.js with libraries which do not
  support the math.js data types.

Math.js can be extended with functions and variables:

```js
// create an instance of math.js
var math = require('mathjs')();

// define new functions and variables
math.import({
    myvalue: 42,
    hello: function (name) {
        return 'hello, ' + name + '!';
    }
});

// defined functions can be used in both JavaScript as well as the parser
math.myvalue * 2;               // 84
math.hello('user');             // 'hello, user!'

var parser = math.parser();
parser.eval('myvalue + 10');    // 52
parser.eval('hello("user")');   // 'hello, user!'
```

External libraries like
[numbers.js](https://github.com/sjkaliski/numbers.js) and
[numeric.js](http://numericjs.com/) can be imported as well.
The libraries must be installed using npm:

    npm install numbers
    npm install numeric

The libraries can be easily imported into math.js using `import`. By default,
existing functions will not be overwritten, and math.js will create a wrapper
function around the imported functions which converts data types like `Matrix`
to primitive types like `Array`.

```js
// create an instance of math.js
var math = require('mathjs')();

// import the numbers.js and numeric.js libraries into math.js
math.import('numbers');
math.import('numeric');

// use functions from numbers.js
math.fibonacci(7);                          // 13
math.eval('fibonacci(7)');                  // 13

// use functions from numeric.js
math.eval('eig([1, 2; 4, 3])').lambda.x;    // [5, -1]
```