lemon-project-template-glpk
view deps/glpk/examples/sorting.mod @ 9:33de93886c88
Import GLPK 4.47
| author | Alpar Juttner <alpar@cs.elte.hu> |
|---|---|
| date | Sun, 06 Nov 2011 20:59:10 +0100 |
| parents | |
| children |
line source
1 /* sorting.mod - how to sort arrays in MathProg */
3 /* Written in GNU MathProg by Andrew Makhorin <mao@gnu.org> */
5 # Sometimes it is necessary to print parameters or variables in the
6 # order of ascending or descending their values. Suppose, for example,
7 # that we have the following subscripted parameter:
9 set I := 1..12;
11 param a{i in I} := Uniform(2, 7);
13 # If we print all its members:
15 printf{i in I} "a[%d] = %g\n", i, a[i];
17 # the output may look like follows:
18 #
19 # a[1] = 2.64156
20 # a[2] = 2.04798
21 # a[3] = 2.14843
22 # a[4] = 4.76896
23 # a[5] = 6.09132
24 # a[6] = 3.27780
25 # a[7] = 4.06113
26 # a[8] = 4.05898
27 # a[9] = 6.63120
28 # a[10] = 6.50318
29 # a[11] = 3.46065
30 # a[12] = 4.69845
31 #
32 # However, we would like the parameter members to appear in the order
33 # of ascending their values.
34 #
35 # Introduce the following auxiliary parameter:
37 param pos{i in I} :=
38 1 + card({j in I: a[j] < a[i] or a[j] = a[i] and j < i});
40 # where pos[i] = k means that in the sorted list member a[i] would
41 # have k-th position, 1 <= k <= |I|. Then introduce another auxiliary
42 # parameter:
44 param ind{k in 1..card(I)} := sum{i in I: pos[i] = k} i;
46 # where ind[k] = i iff pos[k] = i.
47 #
48 # Now, the following statement:
50 printf{k in 1..card(I)} "a[%d] = %g\n", ind[k], a[ind[k]];
52 # prints the parameter members in the desired order:
53 #
54 # a[2] = 2.04798
55 # a[3] = 2.14843
56 # a[1] = 2.64156
57 # a[6] = 3.27780
58 # a[11] = 3.46065
59 # a[8] = 4.05898
60 # a[7] = 4.06113
61 # a[12] = 4.69845
62 # a[4] = 4.76896
63 # a[5] = 6.09132
64 # a[10] = 6.50318
65 # a[9] = 6.63120
67 end;