Forum Discussion

FICO's avatar
FICO
Community Manager
6 years ago

Incompatible data types for operator (Xpress Mosel)

I am currently trying to define a simple model where the goal is to figure out which combination of price, quantity and cost per sale is the profitable as well as calculate the profits for each case as calculated through the objective function.

model "TESTmodel"
uses "mmsheet", "mmxprs"
 
parameters
 MINPROFIT = 1800
 
declarations
  PRODUCTNO = 1..4500
  SALESNO = 1..4500
  COSTNO = 1..4500
 
  PRICE: array(PRODUCTNO) of integer
  QUANTITY: array(SALESNO) of integer
  COSTPERSALE: array(COSTNO) of integer
end-declarations
 
initializations from "SALESDATA.dat"
  PRICE QUANTITY COSTPERSALE
end-initializations
 
Profit:= PRICE * QUANTITY - COSTPERSALE
 
PRICE * QUANTITY - COSTPERSALE >= MINPROFIT
 
maximize(Profit)
writeln("Solution:\n Objective: ", getobjval)
forall(p in PRODUCTNO) writeln(" Total Profit is:", getsol(Profit)
 
end-model

Running the model however returns the following errors instead:

Mosel: E-101 at (22,27) of `testmosel.mos': Incompatible types for operator (`array of integer' * `array of integer' not defined).
Mosel: E-123 at (22,27) of `testmosel.mos': `Profit' is not defined.
Mosel: E-112 at (22,39) of `testmosel.mos': Numeric expression expected for operator `-'.
Mosel: E-101 at (24,18) of `testmosel.mos': Incompatible types for operator (`array of integer' * `array of integer' not defined).
Mosel: E-112 at (24,33) of `testmosel.mos': Numeric expression expected for operator `-'.
Mosel: E-124 at (24,43) of `testmosel.mos': An expression cannot be used as a statement.
Mosel: E-123 at (26,15) of `testmosel.mos': `Profit' is not defined.
Mosel: E-123 at (28,63) of `testmosel.mos': `Profit' is not defined
Failed to parse Mosel source file

Despite my best efforts to debug the code I have failed to eliminate the error messages. I'm very new to the usage of Xpress Mosel so I would appreciate any form of feedback.

fico® xpress

1 Reply

  • FICO's avatar
    FICO
    Community Manager
    6 years ago

    There are several points going wrong here:

    • the first error is explained by the fact that you are using arrays without indices in the arithmetic formulae, the correct form needs to be something like:

    Profit:= sum(p in PRODUCTNO) (PRICE(p) * QUANTITY(p) - COSTPERSALE(p))

    • your program does not contain any optimization objects: what are the decisions to be taken? I assume these may be the entries of the 'QUANTITY' array, in which case this array needs to be declared as 'mpvar' in place of numerical values and you then don't provide any input values for it
    • a couple of closing markers such as 'end-parameters' in the beginning or a closing ')' in line 27 are missing

    The following model compiles correctly, but I am not certain whether this actually corresponds to the optimization problem that you wish to state:

    model "TESTmodel"
uses "mmxprs"
 
parameters
 MINPROFIT = 1800
end-parameters
 
declarations
  PRODUCTNO = 1..4500
  PRICE: array(PRODUCTNO) of integer
  quantity: array(PRODUCTNO) of mpvar
  COSTPERSALE: array(PRODUCTNO) of integer
end-declarations
 
initializations from "SALESDATA.dat"
  PRICE COSTPERSALE   
end-initializations
 
Profit:= sum(p in PRODUCTNO) (PRICE(p) * quantity(p) - COSTPERSALE(p))
 
sum(p in PRODUCTNO) (PRICE(p) * quantity(p) - COSTPERSALE(p)) >= MINPROFIT
 
maximize(Profit)
writeln("Solution:\n Objective: ", getobjval)    ! Same as:   getsol(Profit)
forall(p in PRODUCTNO) writeln(p, ": ", quantity(p).sol)
 
end-model

Related Content

Related Content