1 | /* emacs edit mode for this file is -*- C++ -*- */ |
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2 | /* $Id: fac_cantzass.cc,v 1.7 2004-10-11 10:49:20 Singular Exp $ */ |
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3 | |
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4 | #include <config.h> |
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5 | |
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6 | #include "cf_gmp.h" |
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7 | |
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8 | #include "assert.h" |
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9 | |
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10 | #include "cf_defs.h" |
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11 | #include "cf_random.h" |
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12 | #include "cf_util.h" |
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13 | #include "fac_cantzass.h" |
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14 | #include "fac_sqrfree.h" |
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15 | #include "gmpext.h" |
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16 | |
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17 | int initializeGMP(); |
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18 | |
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19 | static int initialized = initializeGMP(); |
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20 | |
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21 | static CanonicalForm randomPoly( int n, const Variable & x, const CFRandom & gen ); |
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22 | |
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23 | static CFFList CantorZassenhausFactorFFGF( const CanonicalForm & f, int d, int q, const CFRandom & ); |
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24 | |
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25 | static CFFList CantorZassenhausFactorExt( const CanonicalForm & g, int s, MP_INT * q, const CFRandom & gen ); |
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26 | |
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27 | static CFFList distinctDegreeFactorFFGF ( const CanonicalForm & f, int q ); |
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28 | |
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29 | static CFFList distinctDegreeFactorExt ( const CanonicalForm & f, int p, int n ); |
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30 | |
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31 | // calculates f^m % d |
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32 | |
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33 | static CanonicalForm powerMod( const CanonicalForm & f, int m, const CanonicalForm & d ); |
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34 | |
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35 | // calculates f^(p^s) % d |
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36 | |
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37 | static CanonicalForm powerMod( const CanonicalForm & f, int p, int s, const CanonicalForm & d ); |
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38 | |
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39 | // calculates f^((p^s-1)/2) % d |
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40 | |
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41 | static CanonicalForm powerMod2( const CanonicalForm & f, int p, int s, const CanonicalForm & d ); |
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42 | |
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43 | static CanonicalForm powerMod2( const CanonicalForm & f, MP_INT * q, int s, const CanonicalForm & d ); |
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44 | |
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45 | CFFList FpFactorizeUnivariateCZ( const CanonicalForm& f, bool issqrfree, int numext, const Variable alpha, const Variable beta ) |
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46 | { |
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47 | CFFList F, G, H, HH; |
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48 | CanonicalForm fac; |
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49 | ListIterator<CFFactor> i, j, k; |
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50 | int d, q, n = 0; |
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51 | bool galoisfield = getGFDegree() > 1; |
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52 | MP_INT qq; |
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53 | |
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54 | if ( galoisfield ) |
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55 | q = ipower( getCharacteristic(), getGFDegree() ); |
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56 | else |
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57 | q = getCharacteristic(); |
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58 | if ( numext > 0 ) { |
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59 | if ( numext == 1 ) |
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60 | n = getMipo( alpha ).degree(); |
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61 | else |
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62 | n = getMipo( alpha ).degree() * getMipo( beta ).degree(); |
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63 | mpz_init( &qq ); |
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64 | mpz_mypow_ui( &qq, q, n ); |
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65 | } |
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66 | if ( LC( f ).isOne() ) |
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67 | if ( issqrfree ) |
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68 | F.append( CFFactor( f, 1 ) ); |
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69 | else |
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70 | F = sqrFreeFp( f ); |
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71 | else { |
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72 | if ( issqrfree ) |
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73 | F.append( CFFactor( f / LC( f ), 1 ) ); |
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74 | else |
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75 | F = sqrFreeFp( f / LC( f ) ); |
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76 | H.append( LC( f ) ); |
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77 | } |
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78 | for ( i = F; i.hasItem(); ++i ) { |
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79 | d = i.getItem().exp(); |
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80 | if ( numext > 0 ) |
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81 | G = distinctDegreeFactorExt( i.getItem().factor(), q, n ); |
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82 | else |
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83 | G = distinctDegreeFactorFFGF( i.getItem().factor(), q ); |
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84 | for ( j = G; j.hasItem(); ++j ) { |
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85 | if ( numext > 0 ) { |
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86 | if ( numext == 1 ) { |
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87 | AlgExtRandomF tmpalpha( alpha ); |
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88 | HH = CantorZassenhausFactorExt( j.getItem().factor(), j.getItem().exp(), &qq, tmpalpha ); |
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89 | } |
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90 | else { |
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91 | AlgExtRandomF tmpalphabeta( alpha, beta ); |
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92 | HH = CantorZassenhausFactorExt( j.getItem().factor(), j.getItem().exp(), &qq, tmpalphabeta ); |
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93 | } |
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94 | } |
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95 | else if ( galoisfield ) |
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96 | HH = CantorZassenhausFactorFFGF( j.getItem().factor(), j.getItem().exp(), q, GFRandom() ); |
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97 | else |
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98 | HH = CantorZassenhausFactorFFGF( j.getItem().factor(), j.getItem().exp(), q, FFRandom() ); |
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99 | for ( k = HH; k.hasItem(); ++k ) { |
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100 | fac = k.getItem().factor(); |
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101 | H.append( CFFactor( fac / LC( fac ), d ) ); |
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102 | } |
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103 | } |
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104 | } |
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105 | if ( numext > 0 ) |
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106 | mpz_clear( &qq ); |
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107 | #ifdef HAVE_NTL |
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108 | extern int NTLcmpCF( const CFFactor & f, const CFFactor & g ); |
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109 | if(isOn(SW_USE_NTL_SORT)) H.sort(NTLcmpCF); |
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110 | #endif |
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111 | return H; |
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112 | } |
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113 | |
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114 | CFFList distinctDegreeFactorFFGF ( const CanonicalForm & f, int q ) |
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115 | { |
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116 | int i; |
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117 | Variable x = f.mvar(); |
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118 | CanonicalForm g = f, h, r = x; |
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119 | CFFList F; |
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120 | i = 1; |
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121 | while ( g.degree(x) > 0 && i <= g.degree(x) ) { |
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122 | r = powerMod( r, q, g ); |
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123 | h = gcd( g, r - x ); |
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124 | if ( h.degree(x) > 0 ) { |
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125 | F.append( CFFactor( h, i ) ); |
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126 | g /= h; |
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127 | } |
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128 | i++; |
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129 | } |
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130 | ASSERT( g.degree(x) == 0, "fatal fatal" ); |
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131 | return F; |
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132 | } |
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133 | |
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134 | CFFList distinctDegreeFactorExt ( const CanonicalForm & f, int p, int n ) |
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135 | { |
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136 | int i; |
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137 | Variable x = f.mvar(); |
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138 | CanonicalForm g = f, h, r = x; |
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139 | CFFList F; |
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140 | i = 1; |
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141 | while ( g.degree(x) > 0 && i <= g.degree(x) ) { |
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142 | r = powerMod( r, p, n, g ); |
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143 | h = gcd( g, r - x ); |
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144 | if ( h.degree(x) > 0 ) { |
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145 | F.append( CFFactor( h, i ) ); |
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146 | g /= h; |
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147 | } |
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148 | i++; |
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149 | } |
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150 | ASSERT( g.degree(x) == 0, "fatal fatal" ); |
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151 | return F; |
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152 | } |
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153 | |
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154 | CFFList CantorZassenhausFactorFFGF( const CanonicalForm & g, int s, int q, const CFRandom & gen ) |
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155 | { |
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156 | CanonicalForm f = g; |
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157 | CanonicalForm b, f1; |
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158 | int d, d1; |
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159 | Variable x = f.mvar(); |
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160 | |
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161 | if ( (d=f.degree(x)) == s ) |
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162 | return CFFactor( f, 1 ); |
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163 | else while ( 1 ) { |
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164 | b = randomPoly( d, x, gen ); |
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165 | f1 = gcd( b, f ); |
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166 | if ( (d1 = f1.degree(x)) > 0 && d1 < d ) { |
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167 | CFFList firstFactor = CantorZassenhausFactorFFGF( f1, s, q, gen ); |
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168 | CFFList secondFactor = CantorZassenhausFactorFFGF( f/f1, s, q, gen ); |
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169 | return Union( firstFactor, secondFactor ); |
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170 | } else { |
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171 | f1 = gcd( f, powerMod2( b, q, s, f ) - 1 ); |
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172 | if ( (d1 = f1.degree(x)) > 0 && d1 < d ) { |
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173 | CFFList firstFactor = CantorZassenhausFactorFFGF( f1, s, q, gen ); |
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174 | CFFList secondFactor = CantorZassenhausFactorFFGF( f/f1, s, q, gen ); |
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175 | return Union( firstFactor, secondFactor ); |
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176 | } |
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177 | } |
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178 | } |
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179 | } |
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180 | |
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181 | CFFList CantorZassenhausFactorExt( const CanonicalForm & g, int s, MP_INT * q, const CFRandom & gen ) |
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182 | { |
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183 | CanonicalForm f = g; |
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184 | CanonicalForm b, f1; |
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185 | int d, d1; |
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186 | Variable x = f.mvar(); |
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187 | |
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188 | if ( (d=f.degree(x)) == s ) |
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189 | return CFFactor( f, 1 ); |
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190 | else while ( 1 ) { |
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191 | b = randomPoly( d, x, gen ); |
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192 | f1 = gcd( b, f ); |
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193 | if ( (d1 = f1.degree(x)) > 0 && d1 < d ) { |
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194 | CFFList firstFactor = CantorZassenhausFactorExt( f1, s, q, gen ); |
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195 | CFFList secondFactor = CantorZassenhausFactorExt( f/f1, s, q, gen ); |
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196 | return Union( firstFactor, secondFactor ); |
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197 | } else { |
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198 | f1 = gcd( f, powerMod2( b, q, s, f ) - 1 ); |
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199 | if ( (d1 = f1.degree(x)) > 0 && d1 < d ) { |
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200 | CFFList firstFactor = CantorZassenhausFactorExt( f1, s, q, gen ); |
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201 | CFFList secondFactor = CantorZassenhausFactorExt( f/f1, s, q, gen ); |
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202 | return Union( firstFactor, secondFactor ); |
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203 | } |
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204 | } |
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205 | } |
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206 | } |
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207 | |
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208 | CanonicalForm randomPoly( int d, const Variable & x, const CFRandom & g ) |
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209 | { |
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210 | CanonicalForm result = 0; |
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211 | for ( int i = 0; i < d; i++ ) |
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212 | result += power( x, i ) * g.generate(); |
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213 | result += power( x, d ); |
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214 | return result; |
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215 | } |
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216 | |
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217 | CanonicalForm powerMod( const CanonicalForm & f, int m, const CanonicalForm & d ) |
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218 | { |
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219 | CanonicalForm prod = 1; |
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220 | CanonicalForm b = f % d; |
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221 | |
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222 | while ( m != 0 ) { |
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223 | if ( m % 2 != 0 ) |
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224 | prod = (prod * b) % d; |
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225 | m /= 2; |
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226 | if ( m != 0 ) |
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227 | b = (b * b) % d; |
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228 | } |
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229 | return prod; |
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230 | } |
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231 | |
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232 | CanonicalForm powerMod( const CanonicalForm & f, int p, int s, const CanonicalForm & d ) |
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233 | { |
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234 | CanonicalForm prod = 1; |
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235 | CanonicalForm b = f % d; |
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236 | int odd; |
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237 | |
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238 | MP_INT m; |
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239 | |
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240 | mpz_init( &m ); |
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241 | mpz_mypow_ui( &m, p, s ); |
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242 | while ( mpz_cmp_si( &m, 0 ) != 0 ) { |
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243 | odd = mpz_mdivmod_ui( &m, 0, &m, 2 ); |
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244 | if ( odd != 0 ) |
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245 | prod = (prod * b) % d; |
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246 | if ( mpz_cmp_si( &m, 0 ) != 0 ) |
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247 | b = (b*b) % d; |
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248 | } |
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249 | mpz_clear( &m ); |
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250 | return prod; |
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251 | } |
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252 | |
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253 | CanonicalForm powerMod2( const CanonicalForm & f, int p, int s, const CanonicalForm & d ) |
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254 | { |
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255 | CanonicalForm prod = 1; |
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256 | CanonicalForm b = f % d; |
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257 | int odd; |
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258 | |
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259 | MP_INT m; |
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260 | |
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261 | mpz_init( &m ); |
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262 | mpz_mypow_ui( &m, p, s ); |
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263 | mpz_sub_ui( &m, &m, 1 ); |
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264 | mpz_div_ui( &m, &m, 2 ); |
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265 | while ( mpz_cmp_si( &m, 0 ) != 0 ) { |
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266 | odd = mpz_mdivmod_ui( &m, 0, &m, 2 ); |
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267 | if ( odd != 0 ) |
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268 | prod = (prod * b) % d; |
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269 | if ( mpz_cmp_si( &m, 0 ) != 0 ) |
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270 | b = (b*b) % d; |
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271 | } |
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272 | mpz_clear( &m ); |
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273 | return prod; |
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274 | } |
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275 | |
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276 | CanonicalForm powerMod2( const CanonicalForm & f, MP_INT * q, int s, const CanonicalForm & d ) |
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277 | { |
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278 | CanonicalForm prod = 1; |
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279 | CanonicalForm b = f % d; |
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280 | int odd; |
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281 | |
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282 | MP_INT m; |
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283 | |
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284 | mpz_init( &m ); |
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285 | mpz_mypow( &m, q, s ); |
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286 | mpz_sub_ui( &m, &m, 1 ); |
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287 | mpz_div_ui( &m, &m, 2 ); |
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288 | while ( mpz_cmp_si( &m, 0 ) != 0 ) { |
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289 | odd = mpz_mdivmod_ui( &m, 0, &m, 2 ); |
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290 | if ( odd != 0 ) |
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291 | prod = (prod * b) % d; |
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292 | if ( mpz_cmp_si( &m, 0 ) != 0 ) |
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293 | b = (b*b) % d; |
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294 | } |
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295 | mpz_clear( &m ); |
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296 | return prod; |
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297 | } |
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