### Function Input

Left to the graph view you will find a the funtion input text box. Enter your function
in the textbox and either click the enter button or click on the *add* button
on the right of the text box to add the function to the function list.

The function input may include:

- the variable 'x'
- operators such as +, -, and * (see bellow for complete list)
- built-in functions such as trignometric, hyperbolic, log and other functions.
- mathematical constants: 'e', 'pi' and the golden ratio.
- 'e' is the euler constant (see more here)
- 'pi' is the ratio of a circle's circumference to its diameter (see more here).

*yeah, only in the Eucalidean plane. we know.* - 'phi' is the golden ratio. The ratio of any $a$ and $b$ which statifies the equation $\frac{a+b}{a} = \frac{a}{b} = \varphi$ is the golden ratio. The golden ratio is convensionaly denoted with $\varphi$.(see more here).

#### Operators

- '+' the plus symbol can be used between two expressions. For example x+4 or sin(x)+cos(x).
- '-' the minus symbol has two possible uses. Between two expressions like in x-1/2 or (x+5)-(x+4). The second use is for negation of an expression like in -x or -(cos(x) - 4).
- '*' the multipication symbol can be used between two expression like 5*x-1/2
or 5*(cos(pi*x)).

*Note: you must use the multipication sign when multiplying, inputs such as '2x' are not valid, write '2*x'. We intend to support this syntax in the future.* - '/' the division symbol can be used between two expression like -1/(x*5.2) or (x+2)/(x*x+3).
- '^' is used for rasing one expression to the power of another expression like in e^x or x^2-2 or 5*x^3-0.3*x^2+1.

#### Built-in Functions

- Trigonometric Functions like sine, cosine
- Hyperbolic Functions like hyperbolic sine and hyperbolic cosine
- Root and Log Functions
- Special Functions like min, max, ceil, floor

#### The Function List

You can add as many functions as you want to a graph. All functions added will be drawed on the same graph in different colors. You may edit, hide or delete a function from the graph list.

**edit functions:**

to edit a function either click on the function text or use the function's menu
and choose edit. Both options will replace the function text in the list to a text
box just like the one used to add functions. After you edit your function either
press ENTER or click anywhere on the screen. The function will be viewed in a mathematical
format and the graph will be updated.

Note that if the changes you have made to the function are not valid the function
will be reverted to it's previous formula.

**hide functions:**

to hide a function, use the function's menu. Uncheck "show" check box in the menu
and the function will still be availble on the list but not drawed on the graph.
To show the function again on the graph check the "show"'s check box again and the
function will be drawed on the graph.

**remove function from the list:**

to remove a function, use the function's menu. Simply choose "remove" from the menu
and the function will be deleted from the list and the graph.