# fpm

A C++ header-only fixed-point math library. "fpm" stands for "fixed-point math".

It is designed to serve as a drop-in replacement for floating-point types and aims to provide as much of the standard library's functionality as possible with exclusively integers. `fpm`

requires C++11 or higher.

`fpm`

is designed to guard against accidental conversion to and from floats and supports many of the standard C++ maths functions, including trigonometry, power and logarithmic functions, with performance and accuracy generally comparable to alternative libraries.

## Why use fixed-point math?

There are several reasons why you can not or choose not to use floating-point math, but still want a similar type:

- Your target platform lacks an FPU, does not support floating-point operations or its floating-point operations are considerably slower than fixed-point integer operations.
- You require deterministic calculations.

If any of these reasons apply for you, and your problem domain has a clearly outlined range and required resolution, then fixed-point numbers might be a solution for you.

## Quick Start

To use `fpm`

, include its header `<fpm/fixed.hpp>`

and use the `fpm::fixed_16_16`

, `fpm::fixed_24_8`

or `fpm::fixed_8_24`

types as if they were native floating-pointer types:

```
#include <fpm/fixed.hpp> // For fpm::fixed_16_16
#include <fpm/math.hpp> // For fpm::cos
#include <fpm/ios.hpp> // For fpm::operator<<
#include <iostream> // For std::cin, std::cout
int main() {
std::cout << "Please input a number: ";
fpm::fixed_16_16 x;
std::cin >> x;
std::cout << "The cosine of " << x << " radians is: " << cos(x) << std::endl;
return 0;
}
```

To use the fixed-point equivalents of the `<math.h>`

functions such as `sqrt`

, `sin`

and `log`

, include the header `<fpm/math.hpp>`

. To stream fixed-point values to or from streams, include the header `<fpm/ios.hpp>`

.

## Documentation

Please refer to the documentation for detailed information how to use `fpm`

, or skip straight to the performance or accuracy results.

## Contributions

This library is a work-in-progress. We welcome any contributions that improve the functional coverage or the performance or accuracy of the mathematical functions.

## License

See the LICENSE file