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.

Attn Fortran 90/95 users:
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.

Archi (155Kb) - A code for solving delay and neutral differential equations
Archi-L (224Kb) - A version of Archi (incorporating LMDIF from Netlib) for solving unconstrained parameter estimation problems
Archi-N (183Kb) - A version of Archi that uses the NAg library routine E04USF (available in Mark 20 onwards) for solving constrained parameter estimation problems
Archi-N_E04UNF (183Kb) - A version of Archi-N that uses the NAg library routine E04UNF (available in Mark 17 onwards).
Archi-N_E04UPF (183Kb) - A earlier version of Archi-N that used the NAg library routine E04UPF (withdrawn after Mark 18).

Driver Programs for Archi
Programs and data files from the Archi user-guide (21Kb)
Programs from the "A test set of functional differential equations" technical report (304Kb)
Programs for the "Differential-Difference Equations in Economics: On the Numerical Solution of Vintage Capital Growth Models" paper (19Kb)

Driver Programs for Archi-L and Archi-N
Programs and data files for the "Mathematical Modelling of the Interleukin-2 T-cell System: A Comparative Study of Approaches based on Ordinary and Delay Differential Equations" paper (38Kb)
Programs and data files for the "Modelling and analysis of time-lags in some basic patterns of cell proliferation" paper (79Kb)

Miscellaneous Programs
Programs from the "A Fortran 77 code for plotting stability regions" technical report (11Kb)