Math.js is an extensive math library for JavaScript and Node.js.

`Math.js`

comes with a function `math.evaluate`

to evaluate expressions.

In this blog post, we are going to see the `Math.js`

evaluator in action with interactive code snippets powered by the Klipse plugin.

```
Object.keys(math)
```

# Simple expressions

Easy power:

```
math.evaluate('sqrt(3^2 + 4^2)');
```

Implicit multiplication:

```
math.evaluate('(2+3)(4+5)');
```

Complex numbers:

```
math.evaluate('sqrt(-1)').toString();
```

```
math.evaluate('sqrt(1+i)').toString();
```

Easy trigonometry:

```
math.evaluate('cos(pi)')
```

But the real power of `Math.js`

comes with the ability to define symbolic expressions…

# Defining symbolic functions

First, we need to create a `scope`

for our evaluation environment: The `scope`

is a regular JavaScript Object that is used to resolve symbols, and to write assigned variables or function.

```
scope = {}
```

Then, we can create functions:

```
math.evaluate('bar(x,y) = (x+y)(x-y)', scope)
```

And call them:

```
math.evaluate('bar(10,5)', scope)
```

Now, let’s check that for any angle, `sinus squared + cosinus squared`

equals 1:

```
math.evaluate('amp(x,y) = sqrt(x^2 + y^2)', scope)
```

```
math.evaluate('foo(x)=amp(sin(x), cos(x))', scope)
```

```
math.evaluate('foo(pi/2)',scope)
```

I hope that I have been able to trigger your curiousity about Math.js.

And that you cannot wait to use the Klipse plugin on your next blog post.

Happy interactive coding!