# Taz
Taz is Rust library to evaluate a mathematical expression.

For example we can evaluate the following expression:
- *1 + 1*
- *2.0 * (4.43 - 5.99) / 3.0*
- *sqrt(x^2 + y^2)*
- *cos(pi / 4.0)^2 + sin(pi / 4.0)^2*

## Build
Build of Taz is made by [Rust](https://www.rust-lang.org/) tool [Cargo](https://doc.rust-lang.org/cargo/)

To build Taz, you can use the following command:

	*cargo build* to compile in debug mode
	*cargo build --release* to compile in release mode

To launch Taz units tests, you can use the following command:

	*cargo test* to launch tests in debug mode
	*cargo test --release* to launch tests in release mode

## Code Documentation
Taz code documentation is made also by Cargo with the following command:

	*cargo doc* to generate the documentation
	*cargo doc --open* to open the documention in your browser

## Documentation
The evaluation begin by a tokenization. This step transform a string representing the expression to list of tokens which
correspond to infix expression

Then, we convert this infix expression into postfix expression. Indeed an evaluation of postfix expression is easier.

Finally we evaluate the posfix expression by stack method.

In this expression we can use following predefined constant:
- pi: The constant pi
- e: The exponential constant
- c: The speed of light constant

If you want add a new constant, you must go into _src/constants.rs_ file and add it like other constants.

You can also use following predefined functions:
- abs: the absolute value
- sqrt: the square root
- cbrt: the cubic root
- exp: the exponential
- ln: the natural logarithm
- log10: the logarithm with base 10
- log2: the logarithm with base 2
- sin: the sinus
- cos: the cosinus
- tan: the tangent
- asin: the arc sinus
- acos: the arc cosinus
- atan: the arc tangent
- sinh: the hyperbolic sinus
- cosh: the hyperbolic cosinus
- tanh: the hyperbolic tangent
- asinh: the hyperbolic arc sinus
- acosh: the hyperbolic arc cosinus
- atanh: the hyperbolic arc tangent

If you want add a new predefined function, you must go into _src/functions.rs_ file and add it like other predefined functions.