# Headers Inclusion

The easiest way to access to the library is by including the main header:

    #include <boost/numeric/interval.hpp>

This header will include almost all the other headers (except the ones listed as extensions). However, you may not want to access all the functionalities of the library. So this page stands as a reminder for the whole structure of the library. `<boost/numeric/interval.hpp>` is the only header to be located directly under `boost/numeric/`; all the other headers are located in the subdirectory `boost/numeric/interval/`. And each time this documentation will refer to `interval/something.hpp`, it is `<boost/numeric/interval/something.hpp>`.

Please also note that all the following headers are independent and can easily be pre-compiled if necessary (for compilers which support pre-compiled headers of course).

## Function definitions

The following headers contain the definition of the `interval` class and all the friendly functions and operators.

### `interval/interval.hpp`

This header contains the definition and the declaration of the `interval` class. However, this class is templated and the default template parameters are not available by this header. In particular, this header does not provide the default specialization of the `interval` class for the floating-point types (`interval<float>`, `interval<double>` and `interval<long double>`). So, unless you use your own policies, this header is not really useful on its own.

### `interval/utility.hpp`

In this header are all the functions that do not expect any arithmetic property from the base number type. It only expects the bounds to be ordered; but it should not surprise you since it is a requirement of the whole library. You will find in this header the definitions of access and related functions: `lower`, `upper`, `checked_lower`, `checked_upper`, `median`, `width`, `widen`. There are also the set-like functions: `in,` `in_zero`, `empty`, `subset`, `proper_subset`, `overlap`, `singleton`, `equal`, `intersect`, `hull`, `bisect`. Finally, `abs`, `min` and `max` are defined.

### `interval/arith.hpp`

Here are the binary operators `+`, `-`, `*`, `/` and the unary operator `-`.

### `interval/arith2.hpp`

This header defines `fmod`, `square`, `sqrt` and `pow`.

### `interval/transc.hpp`

It is the last of the three headers with mathematical functions; it provides the following functions: `cos`, `sin`, `tan`, `acos`, `asin`, `atan`, `cosh`, `sinh`, `tanh`, `acosh`, `asinh`, `atanh`, `exp` and `log`.

## Policies

The following headers define some policies. They may be needed if you use the default policies.

### `interval/rounded_arith.hpp`

This header defines the three provided rounding policies for the arithmetic functions: `rounded_arith_std`, `rounded_arith_opp`, `rounded_arith_exact`.

### `interval/rounded_transc.hpp`

This header defines the three provided rounding policies for the transcendental functions: `rounded_transc_std`, `rounded_transc_opp`, `rounded_transc_exact`. It is separated from `rounded_arith.hpp` since the transcendental part of the rounding policy is probably less useful than the arithmetic part.

### `interval/hw_rounding.hpp`

Here are full rounding policies for the basic floating-point types. The policies are processor-dependent; and to allow the user code to be portable, they only define the common subset of the hardware available functions, which are the arithmetic functions of the rounding policy.

### `interval/checking.hpp`

This header provides the predefined checking policies: `checking_base`, `checking_no_empty`, `checking_no_nan`, `checking_catch_nan`, `checking_strict`.

### `interval/policies.hpp`

Here are defined the helpers for manipulating policies. It contains `policies` (and so is needed for using default policies), `change_rounding`, `change_checking`, `unprotect`, etc.

## Comparisons

### `interval/compare.hpp`

This header includes all the following headers. They provide some predefined comparison namespaces.

### `interval/compare/explicit.hpp`

The explicit comparison functions `cerlt`, `posge`, etc are defined in this header.

### `interval/compare/lexicographic.hpp`

This header provides `compare::lexicographic`.

### `interval/compare/set.hpp`

This header provides `compare::set`.

## Extensions

The following headers are not included by `interval.hpp` and will usually provide not always desirable capabilities.

### `interval/io.hpp`

Here are defined basic stream operators `<<` and `>>`. They should only be used as a first approach and later be replaced by a customized version.

### `interval/compare/tribool.hpp`

This header provides a comparison namespace `compare::tribool` especially adapted to a tristate boolean.

### `interval/ext/x86_fast_rounding_control.hpp`

This header defines a new rounding policy allowing to workaround the precision problem of the x86 processors (and so speeding up the computations). However, it only is a partial solution and it shouldn't be used when there is a possibility of underflow.

Revised: 2003-01-21
Copyright (c) Guillaume Melquiond, Sylvain Pion, Hervé Brönnimann, 2002.
Polytechnic University.