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! Data file for ’blend.mos’
COST: [85 93]
AVAIL: [60 45]
GRADE: [2.1 6.3]
The initializations from / end-initializations block is new here, telling Mosel where
to get data from to initialize named arrays. The order of the data items in the file does not
have to be the same as that in the initializations block; equally acceptable would have been
the statements
initializations from ’blend.dat’
AVAIL GRADE COST
end-initializations
Alternatively, since all data arrays have the same indices, they may be given in the form of a
single record, such as BLENDDATA in the following data file blendb.dat:
!
[COST AVAIL GRADE]
BLENDDATA: [ [85
60
2.1]
[93
45
6.3] ]
In the initializations block we need to indicate the label of the data record and in which
order the data of the three arrays is given:
initializations from ’blendb.dat’
[COST,AVAIL,GRADE] as ’BLENDDATA’
end-initializations
2.2.3
Re-running the model with new data
There is a problem with the model we have just presented — the name of the file containing the costs date is hard-wired into the model. If we wanted to use a different file, say
blend2.dat, then we would have to edit the model, and recompile it.
Mosel has parameters to help with this situation. A model parameter is a symbol, the value of
which can be set just before running the model, often as an argument of the run command of
the command line interpreter.
model "Blend 2"
uses "mmxprs"
parameters
DATAFILE="blend.dat"
end-parameters
declarations
REV = 125
MINGRADE = 4
MAXGRADE = 5
ORES = 1..2
COST: array(ORES) of real
AVAIL: array(ORES) of real
GRADE: array(ORES) of real
use: array(ORES) of mpvar
end-declarations
!
!
!
!
Unit revenue of product
Minimum permitted grade of product
Maximum permitted grade of product
Range of ores
! Unit cost of ores
! Availability of ores
! Grade of ores (measured per unit of mass)
! Quantities of ores used
! Read data from file
initializations from DATAFILE
COST
AVAIL
Some illustrative examples
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Mosel User Guide