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[Noel Warren <>]

I'm using the Exact_predicates_exact_constructions kernel to construct my Nef polyhedra and I believe I've run into a bug.  The Nef seems to have no problem being stringified.  When I try to rebuild the nef with the string it will often fail.

I try a simple tetrahedron with points (0,0,0)(1,0,0)(0,1,0)(0,0,1) and everything works fine.  But if I change the last point to have a value of (0,0,1.1) it fails.  You might think that the problem has something to do with floats, but it doesn't.  1.5 works fine as does 0.75

As you probably know, the points are represented as a quotient with both the numerator and denominator being integers.  The problem seems to be that when these integers (gmpz) are being output with the << operator they get abbreviated when too long (eg: 2.47698e+15).  This not only leads to a loss in precision but means the file can not be read, as gmpz cannot parse the integer in that format.  Here is my failing tetrahedron example (see fourth point) ...

Selective Nef Complex

standard

vertices   4

halfedges  12

facets     8

volumes    2

shalfedges 24

shalfloops 0

sfaces     8

0 { 0 2, 0 5, 0 1, -2 | 0 0 0 1 } 1

1 { 3 5, 6 11, 2 3, -2 | 1 0 0 1 } 1

2 { 6 8, 12 17, 4 5, -2 | 0 1 0 1 } 1

3 { 9 11, 18 23, 6 7, -2 | 0 0 2.47698e+15 2.2518e+15 } 1

0 { 4, 0, 0 0 | 1 0 0 1 } 1

1 { 6, 0, 0 1 | 0 1 0 1 } 1

2 { 9, 0, 0 3 | 0 0 1 1 } 1

3 { 7, 1, 0 6 | -1 1 0 1 } 1

4 { 0, 1, 0 7 | -1 0 0 1 } 1

5 { 11, 1, 0 9 | -2.2518e+15 0 2.47698e+15 1 } 1

6 { 1, 2, 0 12 | 0 -1 0 1 } 1

7 { 3, 2, 0 13 | 1 -1 0 1 } 1

8 { 10, 2, 0 15 | 0 -2.2518e+15 2.47698e+15 1 } 1

9 { 2, 3, 0 18 | 0 0 -1 1 } 1

10 { 8, 3, 0 19 | 0 2.2518e+15 -2.47698e+15 1 } 1

11 { 5, 3, 0 21 | 2.2518e+15 0 -2.47698e+15 1 } 1

0 { 1, 4 , , 0 | 0 -1 0 0 } 1

1 { 0, 5 , , 1 | 0 1 0 0 } 1

2 { 3, 20 , , 0 | 2.47698e+15 2.47698e+15 2.2518e+15 -2.47698e+15 } 1

3 { 2, 21 , , 1 | -2.47698e+15 -2.47698e+15 -2.2518e+15 2.47698e+15 } 1

4 { 5, 2 , , 0 | -1 0 0 0 } 1

5 { 4, 3 , , 1 | 1 0 0 0 } 1

6 { 7, 0 , , 0 | 0 0 -1 0 } 1

7 { 6, 1 , , 1 | 0 0 1 0 } 1

0 { 0 } 0

1 { 1 } 1

0 { 1, 4, 2, 0, 1, 6, 12, 6 | 0 0 1 0 } 1

1 { 0, 3, 5, 1, 0, 13, 7, 7 | 0 0 -1 0 } 1

2 { 3, 0, 4, 1, 1, 16, 18, 4 | 1 0 0 0 } 1

3 { 2, 5, 1, 2, 0, 19, 17, 5 | -1 0 0 0 } 1

4 { 5, 2, 0, 2, 1, 22, 8, 0 | 0 1 0 0 } 1

5 { 4, 1, 3, 0, 0, 9, 23, 1 | 0 -1 0 0 } 1

6 { 7, 10, 8, 3, 3, 12, 0, 6 | 0 0 1 0 } 1

7 { 6, 9, 11, 4, 2, 1, 13, 7 | 0 0 -1 0 } 1

8 { 9, 6, 10, 4, 3, 4, 22, 0 | 0 1 0 0 } 1

9 { 8, 11, 7, 5, 2, 23, 5, 1 | 0 -1 0 0 } 1

10 { 11, 8, 6, 5, 3, 20, 14, 2 | -2.47698e+15 -2.47698e+15 -2.2518e+15 0 } 1

11 { 10, 7, 9, 3, 2, 15, 21, 3 | 2.47698e+15 2.47698e+15 2.2518e+15 0 } 1

12 { 13, 16, 14, 6, 5, 0, 6, 6 | 0 0 1 0 } 1

13 { 12, 15, 17, 7, 4, 7, 1, 7 | 0 0 -1 0 } 1

14 { 15, 12, 16, 7, 5, 10, 20, 2 | -2.47698e+15 -2.47698e+15 -2.2518e+15 0 } 1

15 { 14, 17, 13, 8, 4, 21, 11, 3 | 2.47698e+15 2.47698e+15 2.2518e+15 0 } 1

16 { 17, 14, 12, 8, 5, 18, 2, 4 | 1 0 0 0 } 1

17 { 16, 13, 15, 6, 4, 3, 19, 5 | -1 0 0 0 } 1

18 { 19, 22, 20, 9, 7, 2, 16, 4 | 1 0 0 0 } 1

19 { 18, 21, 23, 10, 6, 17, 3, 5 | -1 0 0 0 } 1

20 { 21, 18, 22, 10, 7, 14, 10, 2 | -2.47698e+15 -2.47698e+15 -2.2518e+15 0 } 1

21 { 20, 23, 19, 11, 6, 11, 15, 3 | 2.47698e+15 2.47698e+15 2.2518e+15 0 } 1

22 { 23, 20, 18, 11, 7, 8, 4, 0 | 0 1 0 0 } 1

23 { 22, 19, 21, 9, 6, 5, 9, 1 | 0 -1 0 0 } 1

0 { 0, 1 , , , 0 } 0

1 { 0, 0 , , , 1 } 1

2 { 1, 7 , , , 0 } 0

3 { 1, 6 , , , 1 } 1

4 { 2, 13 , , , 0 } 0

5 { 2, 12 , , , 1 } 1

6 { 3, 19 , , , 0 } 0

7 { 3, 18 , , , 1 } 1

/* end Selective Nef complex */