1 | /* emacs edit mode for this file is -*- C++ -*- */ |
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2 | |
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3 | /** |
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4 | * @file cf_char.cc |
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5 | * |
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6 | * getting and setting the characteristic of a finite field |
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7 | **/ |
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8 | |
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9 | #include "config.h" |
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10 | |
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11 | |
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12 | #include "cf_assert.h" |
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13 | |
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14 | #include "cf_defs.h" |
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15 | #include "canonicalform.h" |
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16 | #include "imm.h" |
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17 | #include "cf_primes.h" |
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18 | #include "cf_util.h" |
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19 | #include "int_pp.h" |
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20 | |
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21 | #ifdef HAVE_FLINT |
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22 | #include "FLINTconvert.h" // for __FLINT_RELEASE |
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23 | #endif |
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24 | |
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25 | STATIC_VAR int theCharacteristic = 0; |
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26 | STATIC_VAR int theDegree = 1; |
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27 | |
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28 | void setCharacteristic( int c ) |
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29 | { |
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30 | if ( c == 0 ) |
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31 | { |
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32 | theDegree = 0; |
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33 | CFFactory::settype( IntegerDomain ); |
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34 | theCharacteristic = 0; |
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35 | } |
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36 | else |
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37 | { |
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38 | theDegree = 1; |
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39 | CFFactory::settype( FiniteFieldDomain ); |
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40 | ff_big = c > cf_getSmallPrime( cf_getNumSmallPrimes()-1 ); |
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41 | if (c!=theCharacteristic) |
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42 | { |
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43 | if (c > 536870909) factoryError("characteristic is too large(max is 2^29)"); |
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44 | ff_setprime( c ); |
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45 | } |
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46 | theCharacteristic = c; |
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47 | } |
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48 | } |
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49 | |
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50 | #if !defined(HAVE_NTL) |
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51 | #if !defined(HAVE_FLINT) || (__FLINT_RELEASE<=20600) |
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52 | void setCharacteristic( int c, int n ) |
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53 | { |
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54 | ASSERT( c > 1 && n > 0, "illegal characteristic" ); |
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55 | setCharacteristic( c ); |
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56 | InternalPrimePower::setPrimePower( c, n ); |
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57 | CFFactory::settype( PrimePowerDomain ); |
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58 | } |
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59 | #endif |
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60 | #endif |
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61 | |
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62 | |
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63 | void setCharacteristic( int c, int n, char name ) |
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64 | { |
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65 | ASSERT( c != 0 && n > 1, "illegal GF(q)" ); |
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66 | setCharacteristic( c ); |
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67 | gf_setcharacteristic( c, n, name ); |
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68 | theDegree = n; |
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69 | CFFactory::settype( GaloisFieldDomain ); |
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70 | } |
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71 | |
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72 | int getCharacteristic() |
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73 | { |
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74 | return theCharacteristic; |
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75 | } |
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76 | |
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77 | int getGFDegree() |
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78 | { |
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79 | //ASSERT( theDegree > 0, "not in GF(q)" ); |
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80 | return theDegree; |
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81 | } |
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82 | |
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83 | CanonicalForm getGFGenerator() |
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84 | { |
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85 | ASSERT( theDegree > 1, "not in GF(q)" ); |
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86 | return int2imm_gf( 1 ); |
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87 | } |
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