/* graph.mod - graph visualization */

 /* Written in GNU MathProg by Andrew Makhorin <mao@gnu.org> */

 /* This model creates a picture in EPS format to visualize a graph. */

 param file, symbolic, default "graph.eps";

 /* output file to write the picture */

 param R, default 2;

 /* radius to draw vertices, in mm */

 param n, integer, > 0;

 /* number of vertices */

 set V, default 1..n;

 /* set of vertices */

 set E, within V cross V;

 /* set of edges */

 param x{i in V}, default 50 * cos((i - 1) / card(V) * 8 * atan(1));

 param y{i in V}, default 50 * sin((i - 1) / card(V) * 8 * atan(1));

 /* x[i] and y[i] are coordinates of node i, in mm */

 param x0 := (min{i in V} x[i]) - R - 3.0;

 param y0 := (min{i in V} y[i]) - R - 3.0;

 param x1 := (max{i in V} x[i]) + R + 3.0;

 param y1 := (max{i in V} y[i]) + R + 3.0;

 printf "%%!PS-Adobe-3.0 EPSF-3.0\n" > file;

 printf "%%%%BoundingBox: 0 0 %d %d\n",

       (72 / 25.4) * (x1 - x0), (72 / 25.4) * (y1 - y0) >> file;

 printf "/Helvetica findfont 6 scalefont setfont\n" >> file;

 printf "/mm { 72 mul 25.4 div } def\n" >> file;

 for {(i,j) in E}

 {     printf "newpath\n" >> file;

       printf "%g mm %g mm moveto\n", x[i] - x0, y[i] - y0 >> file;

       printf "%g mm %g mm lineto\n", x[j] - x0, y[j] - y0 >> file;

       printf "closepath\n" >> file;

       printf "stroke\n" >> file;

 }

 for {i in V}

 {     printf "newpath\n" >> file;

       printf "%g mm %g mm %g mm 0 360 arc\n",

          x[i] - x0, y[i] - y0, R >> file;

       printf "closepath\n" >> file;

       printf "gsave 1 1 1 setrgbcolor fill grestore\n" >> file;

       printf "stroke\n" >> file;

       printf "%g mm %g mm moveto\n",

          x[i] - (if i <= 9 then 1.2 else 1.8) - x0,

          y[i] - 0.8 - y0 >> file;

       printf "( %d ) show\n", i >> file;

 }

 printf "showpage\n" >> file;

 printf "%%%%EOF\n" >> file;

 data;

 param

 :  V  :  x     y :=

    1     0    40

    2    38    12

    3    24   -32

    4   -24   -32

    5   -38    12

    6   -19    26

    7    19    26

    8    31   -10

    9     0   -32

   10   -31   -10

   11    -9    12

   12     9    12

   13    14    -5

   14     0   -15

   15   -14    -5

   16     0     0 ;

 set E :=

    (1,*)  6 10 16 12  7

    (2,*)  7  6 16 13  8

    (3,*)  8  7 16 14  9

    (4,*)  9  8 16 15 10

    (5,*) 10  9 16 11  6

    (6,*) 14

    (7,*) 15

    (8,*) 11

    (9,*) 12

   (10,*) 13

   (11,*) 12 15

   (12,*) 13

   (13,*) 14

   (14,*) 15 ;

 end;