Jonathan,
Try:
maximize Anzahl : sum{i in PEOPLE} x[i];
That's the same.
The problem with your equation is that you can't put if-then-else in a
linear equation
cya
On Sat, Apr 5, 2008 at 10:36 AM, Jonathan Klein <[EMAIL PROTECTED]>
wrote:
> Hi,
>
> i havbe a very simple Problem like this:
>
> set PEOPLE;
> var x{i in PEOPLE} binary;
> maximize Anzahl : sum{i in PEOPLE} (if x[i]==1 then 1 else 0);
> data;
> set LEUTE:=Hans Joachen Peter Klaus;
> end;
>
> And i get the Error: operator preceding == has invalid type
>
> I know, that this problem doesn't make sense, but i have i somewhat more
> complex problem in wich i get the same error:
>
>
>
>
> # Berufsinformationstag
>
> set STUDENT;#i
> set CHOICE;#j
> set COURSE;#k
> set GROUP;#l
>
> param Student_Choice {i in STUDENT, j in CHOICE} symbolic in COURSE;#
> Welcher Schüler welche Wünsche hat
> #param Course_Minimum {k in COURSE};#Wie viele Schüler eine Veranstaltung
> minimal braucht
> #param Course_Maximum {k in COURSE};#Wie viele Schüler eine Veranstaltung
> haben darf
> param Satisfaction {j in CHOICE};#für jeden wunsch die Menge, wie
> glücklich er ist
>
>
> var TimeTable{k in COURSE, l in GROUP}, binary;
> var StudentDistribution {i in STUDENT, k in COURSE, l in GROUP} binary ;
>
> # wenn sich der schüler die aktuelle veranstaltung wünscht und in der
> veranstaltung in dieser gruppe ist
> maximize z: sum{i in STUDENT, l in GROUP, k in COURSE, j in CHOICE}
> (if 1==StudentDistribution[i,k,l]
> and k==Student_Choice[i, j]
> then Satisfaction[k] else 0);
>
>
>
>
>
> So i have Students that are in different Courses, in 1 Course per Group.
> They coose 6 Courses and will be in 4 (1 in each group). If they are in a
> grout that the have choosen, they are happy.
> So i have to check for every Choice of every Student in every Course in
> every Group if the student is in this course in this group and if he had
> choosen it. If so, he gets as much happiness as his choice had importance.
>
> At the end i need to know form every Student in which courses he ist an
> which courses in which group have to take place, so i have choosen the
> binary variables.
>
> I dont konw why the types should not match, because StudentDistribution
> ist binary, so i can only be 0 or 1 an Student_Choice has to be a COURSE.
>
> I studiet the language reference manual for a long time and looked at many
> examples with if/then/else but i still have no idea what i'm doing wrong.
>
> PS: I use C++ for 5 years now, but im relativly new to GNU MathProg :(
>
> I would be very gald for every help.
>
> Jonathan
>
>
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>
--
Leandro B. Barcelos
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