lemon-project-template-glpk

comparison deps/glpk/examples/sorting.mod @ 9:33de93886c88

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Import GLPK 4.47
author Alpar Juttner <alpar@cs.elte.hu>
date Sun, 06 Nov 2011 20:59:10 +0100
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1 /* sorting.mod - how to sort arrays in MathProg */
2
3 /* Written in GNU MathProg by Andrew Makhorin <mao@gnu.org> */
4
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:
8
9 set I := 1..12;
10
11 param a{i in I} := Uniform(2, 7);
12
13 # If we print all its members:
14
15 printf{i in I} "a[%d] = %g\n", i, a[i];
16
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:
36
37 param pos{i in I} :=
38 1 + card({j in I: a[j] < a[i] or a[j] = a[i] and j < i});
39
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:
43
44 param ind{k in 1..card(I)} := sum{i in I: pos[i] = k} i;
45
46 # where ind[k] = i iff pos[k] = i.
47 #
48 # Now, the following statement:
49
50 printf{k in 1..card(I)} "a[%d] = %g\n", ind[k], a[ind[k]];
51
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
66
67 end;