correcting...
You can't put the variable in the test sentence of the if-then-else.
On Sat, Apr 5, 2008 at 2:13 PM, Leandro Barcelos
<address@hidden <mailto:address@hidden>> wrote:
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
<address@hidden <mailto:address@hidden>> 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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Leandro B. Barcelos