someone wrote:

"In linear programming you usually don't have enough equations or  
variable to solve a set of equations (rarely do you have complete  
information in real life to generate a complete set of equations or  
to know all variables). You usually know constraints for variables.  
It's really not programming like when you think of computer programming."

yes, that is the issue here. i have been working on developing dog diets for my 4 dogs, 2 of which are special needs cases.  so far, spreadsheet has been good using gnumeric. the grid is 13 x 11 cells.
along the 'x' coordinate i have the conversion factor,& multiplier (also called index number) for the protein, fat, carbohydrate and calories of the ingredients, and the percentages of the totals. each with its appropriate formula.

the ingredients are on the 'y' coordinate and vary but usually are based on; chicken, egg, milk, cheese, oil, carb source. here is where i would probably like to mix things up more as so the amounts by putting in the 'desired outcome' for say, the nutrient index of protein or the percentage of protein, or both, and having the program make the changes in the amounts. 
instead, what i am doing is constantly going back and forth, changing amounts by small bits and waiting to see how it changes all the other values, then seeing how to 'fix' the fix. aghhh.
it's complicated to explain.

each sub group : protein, fat, carb. is evaluated separately from and also, together with the other group and as a percentage of the whole calorie count. anyway, 

my husband, who is an engineer & smarter than me on math things said to look in linux for a program (but he only uses microsoft :( )  little consolation since there is not a program for free in microsoft either. 
he knows that if there is something free it will be in linux.

i looked at the descriptions of COIN-OR and maxima, they looked promising; to someone who can understand programming. which , again , is not me :(.
anyone who knows how to do that, does not need a gui to run linux like i do.

i am thinking that my best solution is probably to spend hours doing what i did this weekend, and then not changing it too much, just re-evaluating it based on the dogs' conditioning (weight, coat, general health, attitude) every few months.

since i'm not selling it it's just for MY dogs, i guess i can do that. the basic diet so far for the 4 dogs took 6 hours. and i can tweak it from here i guess.

well, thx for the ideas, if someone does here of a free, cheap gui based model; don't forget about me :)


-- 
betty i.
www.webcanine.com
information for people 
who care for dogs.

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