The GNU Octave built-in floating-point routines are not useful for interval arithmetic: Their results depend on hardware, system libraries and compilation options.
The interval package handles all arithmetic functions with the help of the [http://www.mpfr.org/ GNU MPFR library]. With MPFR it is possible to compute system-independent, valid and tight enclosures of the correct results for most functions. However, it should be noted that some reverse operations and matrix operations do not exists in GNU MPFR and therefore cannot be computed with the same accuracy.
== Installation ==
The interval package is available at Octave Forge [http://octave.sourceforge.net/interval/] and can be installed from within GNU Octave (version ≥ 3.8.2). During installation parts of the package are compiled for the target system, which requires the GNU MPFR development libraries (version ≥ 3.1.0) to be installed.
<span style="opacity:.5">octave:1> </span>pkg install -forge interval
<span style="opacity:.5">octave:2> </span>pkg load interval
The ''development version'' may be obtained from its mercurial repository. For convenience a Makefile target allows running the package from source.
hg clone http://hg.code.sf.net/p/octave/interval octave-interval
cd octave-interval; make run
== Quick start introduction ==