spielwiese
Last change
on this file since 287cc8 was
287cc8,
checked in by Hans Schönemann <hannes@…>, 14 years ago
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ntl 5.5.2
git-svn-id: file:///usr/local/Singular/svn/trunk@12402 2c84dea3-7e68-4137-9b89-c4e89433aadc
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-
Property mode set to
100644
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File size:
1.4 KB
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1 | |
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2 | #include <NTL/FacVec.h> |
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3 | #include <NTL/ZZ.h> |
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4 | |
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5 | #include <NTL/new.h> |
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6 | |
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7 | NTL_START_IMPL |
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8 | |
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9 | NTL_vector_impl(IntFactor,vec_IntFactor) |
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10 | |
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11 | static |
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12 | void swap(IntFactor& x, IntFactor& y) |
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13 | { |
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14 | IntFactor t; |
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15 | |
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16 | t = x; x = y; y = t; |
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17 | } |
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18 | |
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19 | static |
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20 | void FindMin(FacVec& v, long lo, long hi) |
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21 | { |
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22 | long minv = 0; |
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23 | long minp = -1; |
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24 | long i; |
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25 | |
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26 | for (i = lo; i <= hi; i++) { |
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27 | if (minv == 0 || v[i].val < minv) { |
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28 | minv = v[i].val; |
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29 | minp = i; |
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30 | } |
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31 | } |
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32 | |
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33 | swap(v[lo], v[minp]); |
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34 | } |
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35 | |
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36 | |
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37 | void FactorInt(FacVec& fvec, long n) |
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38 | { |
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39 | if (n <= 1) Error("internal error: FactorInt(FacVec,long n) with n<=1"); |
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40 | |
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41 | if (NTL_OVERFLOW(n, 1, 0)) |
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42 | Error("internal error: FactorInt(FacVec,long n) with n too large"); |
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43 | |
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44 | long NumFactors; |
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45 | long q; |
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46 | |
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47 | fvec.SetLength(2*NextPowerOfTwo(n)); |
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48 | |
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49 | NumFactors = 0; |
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50 | q = 2; |
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51 | |
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52 | while (n != 1) { |
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53 | if (n%q == 0) { |
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54 | fvec[NumFactors].q = q; |
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55 | n = n/q; |
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56 | fvec[NumFactors].a = 1; |
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57 | fvec[NumFactors].val = q; |
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58 | while (n%q == 0) { |
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59 | n = n/q; |
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60 | (fvec[NumFactors].a)++; |
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61 | fvec[NumFactors].val *= q; |
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62 | } |
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63 | fvec[NumFactors].link = -1; |
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64 | NumFactors++; |
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65 | } |
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66 | |
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67 | q++; |
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68 | } |
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69 | |
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70 | fvec.SetLength(2*NumFactors-1); |
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71 | |
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72 | long lo = 0; |
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73 | long hi = NumFactors - 1; |
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74 | |
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75 | while (lo < hi) { |
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76 | FindMin(fvec, lo, hi); |
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77 | FindMin(fvec, lo+1, hi); |
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78 | hi++; |
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79 | fvec[hi].link = lo; |
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80 | fvec[hi].val = fvec[lo].val * fvec[lo+1].val; |
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81 | lo += 2; |
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82 | } |
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83 | } |
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84 | |
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85 | |
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86 | |
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87 | NTL_END_IMPL |
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