lemon-project-template-glpk
annotate 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 |
| rev | line source |
|---|---|
| alpar@9 | 1 /* sorting.mod - how to sort arrays in MathProg */ |
| alpar@9 | 2 |
| alpar@9 | 3 /* Written in GNU MathProg by Andrew Makhorin <mao@gnu.org> */ |
| alpar@9 | 4 |
| alpar@9 | 5 # Sometimes it is necessary to print parameters or variables in the |
| alpar@9 | 6 # order of ascending or descending their values. Suppose, for example, |
| alpar@9 | 7 # that we have the following subscripted parameter: |
| alpar@9 | 8 |
| alpar@9 | 9 set I := 1..12; |
| alpar@9 | 10 |
| alpar@9 | 11 param a{i in I} := Uniform(2, 7); |
| alpar@9 | 12 |
| alpar@9 | 13 # If we print all its members: |
| alpar@9 | 14 |
| alpar@9 | 15 printf{i in I} "a[%d] = %g\n", i, a[i]; |
| alpar@9 | 16 |
| alpar@9 | 17 # the output may look like follows: |
| alpar@9 | 18 # |
| alpar@9 | 19 # a[1] = 2.64156 |
| alpar@9 | 20 # a[2] = 2.04798 |
| alpar@9 | 21 # a[3] = 2.14843 |
| alpar@9 | 22 # a[4] = 4.76896 |
| alpar@9 | 23 # a[5] = 6.09132 |
| alpar@9 | 24 # a[6] = 3.27780 |
| alpar@9 | 25 # a[7] = 4.06113 |
| alpar@9 | 26 # a[8] = 4.05898 |
| alpar@9 | 27 # a[9] = 6.63120 |
| alpar@9 | 28 # a[10] = 6.50318 |
| alpar@9 | 29 # a[11] = 3.46065 |
| alpar@9 | 30 # a[12] = 4.69845 |
| alpar@9 | 31 # |
| alpar@9 | 32 # However, we would like the parameter members to appear in the order |
| alpar@9 | 33 # of ascending their values. |
| alpar@9 | 34 # |
| alpar@9 | 35 # Introduce the following auxiliary parameter: |
| alpar@9 | 36 |
| alpar@9 | 37 param pos{i in I} := |
| alpar@9 | 38 1 + card({j in I: a[j] < a[i] or a[j] = a[i] and j < i}); |
| alpar@9 | 39 |
| alpar@9 | 40 # where pos[i] = k means that in the sorted list member a[i] would |
| alpar@9 | 41 # have k-th position, 1 <= k <= |I|. Then introduce another auxiliary |
| alpar@9 | 42 # parameter: |
| alpar@9 | 43 |
| alpar@9 | 44 param ind{k in 1..card(I)} := sum{i in I: pos[i] = k} i; |
| alpar@9 | 45 |
| alpar@9 | 46 # where ind[k] = i iff pos[k] = i. |
| alpar@9 | 47 # |
| alpar@9 | 48 # Now, the following statement: |
| alpar@9 | 49 |
| alpar@9 | 50 printf{k in 1..card(I)} "a[%d] = %g\n", ind[k], a[ind[k]]; |
| alpar@9 | 51 |
| alpar@9 | 52 # prints the parameter members in the desired order: |
| alpar@9 | 53 # |
| alpar@9 | 54 # a[2] = 2.04798 |
| alpar@9 | 55 # a[3] = 2.14843 |
| alpar@9 | 56 # a[1] = 2.64156 |
| alpar@9 | 57 # a[6] = 3.27780 |
| alpar@9 | 58 # a[11] = 3.46065 |
| alpar@9 | 59 # a[8] = 4.05898 |
| alpar@9 | 60 # a[7] = 4.06113 |
| alpar@9 | 61 # a[12] = 4.69845 |
| alpar@9 | 62 # a[4] = 4.76896 |
| alpar@9 | 63 # a[5] = 6.09132 |
| alpar@9 | 64 # a[10] = 6.50318 |
| alpar@9 | 65 # a[9] = 6.63120 |
| alpar@9 | 66 |
| alpar@9 | 67 end; |