## xxcalc-rs

An embeddable or a standalone robust floating-point polynomial calculator written in Rust.

This project is a Rust crate (library) which provides a floating-point numbers calculator in an easy to use API. Furthermore a basic unit of computation is a polynomial, so multiple arithmetic operations can be done using `x`

symbols.

You can use this library in your own projects as mathematical evaluator or as a standalone, command line calculator by using `xxcalc`

binary. Internally it uses hand-made tokenizer and a Dijskatra's shunting-yard algorithm to convert infix form into Reverse Polish Notation, which is later evaluated. Please see the complete documentation for the implementation details.

## Binary

`xxcalc`

can be used to replace common `bc`

Unix-utility. It has a support for addition, subtraction, multiplication, division and exponentation built-in.

Here is an example session with the calculator:

```
>>> (3+(4-1))*5
30
>>> 2 * x + 0.5 = 1
0.25
>>> 2x + 1 = 2(1-x)
0.25
>>> (x^3+2x-1)^3
x^9+6x^7-3x^6+12x^5-12x^4+11x^3-12x^2+6x-1
>>> bind((x^3+2x-1)^3, 1)
8
>>> log(128, 2)
7
```

### Features

`+`

,`-`

,`*`

,`/`

,`^`

operators on floating-point polynomials- scientific notation and negative numbers
- polynomials representation using
`x`

symbol - solving linear equations solver using
`=`

operator `log(number, base)`

,`log10(number)`

,`bind(polynomial, x value)`

built-in functions`pi`

and`e`

constants- input read from stdin (can be used for piping)
- interactive readline-like mode with history

### Installation

You need Rust programming language environment (works with stable, beta and nighly channels). If you don't have it already installed please use rustup.rs to easily install the complete environment. Then you can install packaged version from the crates.io using `cargo install xxcalc --features interactive`

.

#### Compilation

The basic compilation process from the source is just running `cargo`

in command line:

```
$ cargo build --release
$ ./target/release/xxcalc
2+2
4
```

Then you can copy the `xxcalc`

binary wherever you prefer (like `/usr/local/bin`

), however this builds a non-interactive version of the binary, with no support for history completion.

In order to build the calculator with support for history (stored in `~/.xxcalcrs_history`

), you need it enable `interactive`

feature (it will automatically resolve dependencies to `rustyline`

):

```
$ cargo build --release --features interactive
$ ./target/release/xxcalc
>>> 2+2
4
```

### Benchmarks

Coming soon. It is at least 2.5 times faster than `bc`

and incomparable quicker than GNU Octave.

## Library

The `xxcalc`

calculator provides a clean and well documented API. Please see its documentation.

The library builds on stable, beta and nighly channels and require no additional dependencies, unless interactive feature is enabled. Therefore you can easily add mathematical expressions evaluator into your project.

The calculator is meant to be extensible -- you can register your own functions or constants. You can even change tokenizer, parser or an evaluator into your own. Furthermore a `Polynomial`

is a standalone type which can be used in your projects without usage of other features of the calculator.

### Usage

Add `xxcalc`

as dependency in your `Cargo.toml`

, then just use `xxcalc`

crate and the parts you need.

```
# Cargo.toml
[dependencies]
xxcalc = "0.2.1"
```

```
extern crate xxcalc;
use xxcalc::linear_solver::LinearSolver;
use xxcalc::calculator::Calculator;
fn main() {
println!("The result is {}", LinearSolver.process("2+2").unwrap());
}
```

Many usage hints and scenarios are available in the documentation.

### Tests

The projects is thoroughly unit tested, some examples are directly provided in the documentation. Use `cargo test`

to run the unit tests.

If you have a Rust nighly compiler you can run some built-in bencharks using `cargo bench`

. Some more extensive benchmarks (using large expressions) can be run using `cargo bench -- --ignored`

.

## License

The project is licensed under MIT license, the author is Amadeusz Juskowiak [email protected], feel free to ask any questions or to hire me.