The Ryacas package is an interface between R and the computer algebra system, yacas. It includes an R to yacas parser/translator and an OpenMath/XML to R parser/translator. See: http://ryacas.googlecode.com
On Sat, Jul 19, 2008 at 11:03 PM, Stuart Nettleton <[EMAIL PROTECTED]> wrote: > Tolga, > Your issue seems to be a common one at present. While I am relatively new to > R (and would welcome being corrected), I haven't been able to find an > existing module to parse algebraic equations and build acyclic networks (for > the objective function and each constraint) to submit to solving routines > (such as optim, BB, Patrick Burns' genopt from S Poetry, Algencan etc). > Certainly there are the components to build one, for example topological > sort packages like mathgraph and Carter Butts' network. I have implemented > acyclic networks in three major projects and so I have started to > contemplate the missing package in both R and Mathematica. At this point I > am significantly further advanced in Mathematica, building from Eric > Swanson's excellent perturbationAIM package. Yet it seems slightly odd to me > that the required functionality hasn't been developed in R up to this point > in time. Many people need this functionality, the network algorithms have > been around for forty years and there are many solvers, even open source > ones like ipopt. Of course, the "big guns" in this field are GAMS and AMPL > and it is perhaps their overwhelming presence or respect for the developers > of these packages that has led R developers to be somewhat cautious about > releasing code in this area. However, there are already alternatives. For a > quasi open source version of AMPL you could use Dr Ampl > (http://www.gerad.ca/~orban/drampl/ ) or write your problem in GAMS or AMPL > format and submit to the Neos server either directly > (http://neos.mcs.anl.gov/neos/) or by using pyneos.py > (www.gerad.ca/~orban/pyneos/pyneos.py). I really hope this gets worked out > in R at some stage! > Stuart > > On Sun, 20 Jul 2008 08:10:35 +1000, <[EMAIL PROTECTED]> wrote: > >> Dear R Users, >> I am looking for some guidance on setting up an optimisation in R with >> non-linear constraints. >> >> Here is my simple problem: >> - I have a function h(inputs) whose value I would like to maximise >> - the 'inputs' are subject to lower and upper bounds >> - however, I have some further constraints: I would like to constrain the >> values for two other separate function f(inputs) and g(inputs) to be >> within >> certain bounds >> >> This means the 'inputs' must not only lie within the bounds specified by >> the 'upper' and 'lower' bounds, but they must also not take on values such >> that f(inputs) and g(inputs) take on values outside defined values. h, f >> and g are all non-linear. >> >> I believe constroptim would work if f and g were linear. Alas, they are >> not. Is there any other way I can achieve this in R ? >> >> Thanks in advance, >> Tolga >> >> Generally, this communication is for informational purposes only >> and it is not intended as an offer or solicitation for the purchase >> or sale of any financial instrument or as an official confirmation >> of any transaction. In the event you are receiving the offering >> materials attached below related to your interest in hedge funds or >> private equity, this communication may be intended as an offer or >> solicitation for the purchase or sale of such fund(s). All market >> prices, data and other information are not warranted as to >> completeness or accuracy and are subject to change without notice. >> Any comments or statements made herein do not necessarily reflect >> those of JPMorgan Chase & Co., its subsidiaries and affiliates. >> >> This transmission may contain information that is privileged, >> confidential, legally privileged, and/or exempt from disclosure >> under applicable law. 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