libiir

Library

GPLv3

Active

libiir provides a C API for implementing IIR filters. It allows filters to be represented as a set of coefficients (and provides some simple well-known Butterworth filter types) and arbitrary chains of coefficient sets.

Downloads

You can download the latest version by cloning the git repository:

git clone git://git.lwithers.me.uk/libiir

Released Files.
Version	Date	Source	GPG Signature (key)	Online docs	Documentation	Doc Signature
1.0.2	2012-03-16	.tar.bz2	.tar.bz2.asc	Here	.tar.bz2	.tar.bz2.asc
1.0.1	2011-04-15	.tar.bz2	.tar.bz2.asc	Here	.tar.bz2	.tar.bz2.asc
1.0.0	2010-11-08	.tar.bz2	.tar.bz2.asc	Here	.tar.bz2	.tar.bz2.asc

Older releases may be found here.

News

2012-03-16T11:00Z

1.0.2 released
High-order Butterworth filters now use 2nd order components rather than 4th order. This should avoid numerical instability.

2011-04-15T19:12Z

1.0.1 released
Fixed a bug in iir_parse_n() which would cause filters after the first to be corrupted in memory.
Improved the initial conditions by assuming a steady-state input of the same value as the sample and a steady-state output of the input multiplied by the DC gain of the filter (previously the output was assumed to be 0).
Added functionality to compute the filter response at a given frequency using the Z transform method and a filter plot test program which uses this method rather than the previous simulation version. Requires ISO C99 complex types (<complex.h>).

2010-11-08T15:22Z

1.0.0 released
Initial release.