Hi Robbie, On 9/15/12, Robbie Morrison <[email protected]> wrote:
> I cannot help you with the MathProg code. But I do use > discounted cash flow calculations. So here are some > observations: > > IRR is not NPV. You need to get the right formula from > wikipedia. It seems to me (but I could be badly > mistaken) that NPV is an explicit equation and IRR is > implicit. NPV takes the discount rate as parameter, > hence no need for numerical methods like > Newton-Raphson. You just need NPV then? Yes, my model is maximising NPV (as you can in this screenshot below). https://picasaweb.google.com/116847891529748214201/ForestValueFOLPIBasedFormulationForestValuationForestEstateModellingAndWoodflowModel#5787997991655844226 > Once you get your formula working, check it against the > appropriate spreadsheet function. In my case, I used: > PMT(rate, periods, investment value, future value). > That way you will align with the industry conventions. > > You can sometimes break the formulas up into parts for > ease of coding. > > You will need to decide how to deal with all the corner > cases: can the interest rate be zero for instance, do > you wish to check, what happens then, and so on .. > > One reference that I never used, but looked interesting: > > Ødegaard, Bernt Arne. 2007. Financial numerical > recipes in C++ -- April 2007. Software > documentation. > > http://finance.bi.no/~bernt/gcc_prog > http://finance.bi.no/~bernt/gcc_prog/recipes/recipes.pdf > http://finance.bi.no/~bernt/gcc_prog/recipes/finrecipes.tar.gz These financial recipes are interesting. It might be good to include some of these financial functions (NPV, IRR, etc.) in the MathProg. It will facilitates easy generating of reports. > Finally, try googling with "GAMS". This must be a > common enough task for GAMS users. This one looks > related (but care with the download, the filename > contains comma chars): > > Wu, Jinzhuo, Mark Sperow, and Jingxin Wang. 2010. > Economic feasibility of a woody biomass-based > ethanol plant in central Appalachia. Journal of > Agricultural and Resource Economics v35 no3 > p522-544. > > http://purl.umn.edu/99118 > > http://ageconsearch.umn.edu/bitstream/99118/2/JARE,Dec2010,%2311F,pp522-544.pdf Thanks for posting the URL of this paper. I am also interest in Bioenergy modelling especially includes estate modelling (i.e. forest estate for biomass for energy and farm estate for producing biomass or biofuels for certain crop). I just browse the pdf and it seems that it has good methodology in using IRR and NPV as can see in the graphs. Thanks. Noli _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
