Archi is a Fortran 77 code that was developed as part of my Ph.D. during the period 1989-1992. The code was later extended so that it could be used for estimating unknown scalar parameters in delay and neutral differential equations. This was achieved by incorporating the unconstrained minimization algorithm LMDIF, available from Netlib, into Archi to produce Archi-l. Another version of Archi that allows constrained parameter estimation, Archi-n, was developed using the NAg library routine E04UPF.
All three codes are downloadable from this page, although you will need access to the NAg library in order to use Archi-n. The only restriction on their use is that they cannot be used, either directly or indirectly by incorporation into other codes, for commercial use without prior permission. The user-guide for all three versions of Archi is available as Manchester Centre for Computational Mathematics technical report number 283.
Whilst there is no requirement to register their use, I am always interested to know what application areas they are being used in.
Please note that Archi, Archi-l and Archi-n are very much research codes and thus, although the underlying differential equation solver has had several years of testing, they cannot be guaranteed to be error-free or infallible. Thus these codes are used at your own risk.
2nd June 2003 Earlier versions of Archi (and its variants) used three reserved Fortran 90 words (RANGE, SCAN and SIZE) that generated compilation warnings and/or errors when compiled using a Fortran 90/95 compiler. As SCAN and SIZE were purely internal routines, they have been renamed to avoid these problems. However, because RANGE is a user-callable routine that appears in both user documentation and driver codes, this routine name has not been updated. If you do experience compliation problems relating to this naming conflict, then the routine can simply be renamed to RANGET.