# EquationExplorer

## Frequently Asked Questions

### What can I graph with it?

The default "Equation" function of *EquationExplorer* can graph most algebraic equations, both implicit and explicit.

Here are a few interesting implicit equations to get you started:

- Circle
- Ellipse
- Superellipse
- Cardioid
- Limacon
- Elliptic Curve
- Mordell Curve
- Heart Curve
- Quadrifolium
- Knot Curve

It also supports non-implicit functions, such as:

The Vector Field grapher supports most 2-dimensional vector fields, such as:

The i and j variables are the x and y unit vectors, so the equation 'i+2j' is a vector one unit in the x direction and two units in the y direction.

The Parametric grapher graphs parametric equations, with the input a time dependent position vector. Variables i and j are the x and y unit vectors.

Here are a few examples:

### What special functions can be used in equations?

- sin — Sine (radians)
- cos — Cosine (radians)
- tan — Tangent (radians)
- atan — Inverse Tangent (result in radians)
- acos — Inverse Cosine (result in radians)
- asin — Inverse Sine (result in radians)
- round — Round to nearest integer
- sqrt — Square Root
- abs — Absolute Value
- ln — Natural Logarithm

### How can I share a graph?

The URL is unique to each graph and will automatically update as the graph is edited.

### How can I save a graph as an image?

Right click on the graph and choose "Save Image As..." in most browsers.

### What happens when I use the variable `m` in an equation?

Buttons will appear below the input to allow you to adjust the value of `m`. That value will be substituted back into the equation at each use of the variable. This allows you to easily experiment on how a change to a constant will affect the graph.

Many of the example equations listed above use this feature.

### Can I re-use the parser or graphing engine elsewhere?

The source is released under the GPL and can be found on github. Relevant files are:

- tdop_math.js - the parser
- tokens.js - the TDOP tokenizer
- graph.js - the graphing engine
- ui.js - the user interface

You can experiment with the parser at its test page

### Have another question?

Post on the Feedback page