1 | /*****************************************************************************\ |
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2 | * Computer Algebra System SINGULAR |
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3 | \*****************************************************************************/ |
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4 | /** @file facBivar.h |
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5 | * |
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6 | * bivariate factorization over Q(a) |
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7 | * |
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8 | * @author Martin Lee |
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9 | * |
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10 | * @internal @version \$Id$ |
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11 | * |
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12 | **/ |
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13 | /*****************************************************************************/ |
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14 | |
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15 | #ifndef FAC_BIVAR_H |
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16 | #define FAC_BIVAR_H |
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17 | |
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18 | #include <config.h> |
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19 | |
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20 | #include "assert.h" |
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21 | |
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22 | #include "facFqBivarUtil.h" |
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23 | #include "DegreePattern.h" |
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24 | #include "cf_util.h" |
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25 | #include "facFqSquarefree.h" |
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26 | #include "cf_map.h" |
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27 | #include "cfNewtonPolygon.h" |
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28 | #include "algext.h" |
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29 | |
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30 | /// @return @a biFactorize returns a list of factors of F. If F is not monic |
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31 | /// its leading coefficient is not outputted. |
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32 | CFList |
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33 | biFactorize (const CanonicalForm& F, ///< [in] a bivariate poly |
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34 | const Variable& v ///< [in] some algebraic variable |
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35 | ); |
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36 | |
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37 | /// factorize a squarefree bivariate polynomial over \f$ Q(\alpha) \f$. |
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38 | /// |
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39 | /// @ return @a ratBiSqrfFactorize returns a list of monic factors, the first |
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40 | /// element is the leading coefficient. |
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41 | #ifdef HAVE_NTL |
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42 | inline |
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43 | CFList |
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44 | ratBiSqrfFactorize (const CanonicalForm & G, ///< [in] a bivariate poly |
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45 | const Variable& v= Variable (1) ///< [in] algebraic variable |
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46 | ) |
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47 | { |
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48 | CFMap N; |
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49 | CanonicalForm F= compress (G, N); |
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50 | CanonicalForm contentX= content (F, 1); |
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51 | CanonicalForm contentY= content (F, 2); |
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52 | F /= (contentX*contentY); |
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53 | CFFList contentXFactors, contentYFactors; |
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54 | if (v.level() != 1) |
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55 | { |
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56 | contentXFactors= factorize (contentX, v); |
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57 | contentYFactors= factorize (contentY, v); |
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58 | } |
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59 | else |
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60 | { |
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61 | contentXFactors= factorize (contentX); |
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62 | contentYFactors= factorize (contentY); |
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63 | } |
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64 | if (contentXFactors.getFirst().factor().inCoeffDomain()) |
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65 | contentXFactors.removeFirst(); |
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66 | if (contentYFactors.getFirst().factor().inCoeffDomain()) |
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67 | contentYFactors.removeFirst(); |
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68 | if (F.inCoeffDomain()) |
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69 | { |
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70 | CFList result; |
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71 | for (CFFListIterator i= contentXFactors; i.hasItem(); i++) |
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72 | result.append (N (i.getItem().factor())); |
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73 | for (CFFListIterator i= contentYFactors; i.hasItem(); i++) |
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74 | result.append (N (i.getItem().factor())); |
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75 | if (isOn (SW_RATIONAL)) |
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76 | { |
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77 | normalize (result); |
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78 | result.insert (Lc (G)); |
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79 | } |
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80 | return result; |
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81 | } |
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82 | mat_ZZ M; |
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83 | vec_ZZ S; |
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84 | F= compress (F, M, S); |
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85 | CFList result= biFactorize (F, v); |
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86 | for (CFListIterator i= result; i.hasItem(); i++) |
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87 | i.getItem()= N (decompress (i.getItem(), M, S)); |
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88 | for (CFFListIterator i= contentXFactors; i.hasItem(); i++) |
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89 | result.append (N(i.getItem().factor())); |
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90 | for (CFFListIterator i= contentYFactors; i.hasItem(); i++) |
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91 | result.append (N (i.getItem().factor())); |
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92 | if (isOn (SW_RATIONAL)) |
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93 | { |
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94 | normalize (result); |
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95 | result.insert (Lc (G)); |
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96 | } |
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97 | return result; |
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98 | } |
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99 | |
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100 | /// factorize a bivariate polynomial over \f$ Q(\alpha) \f$ |
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101 | /// |
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102 | /// @return @a ratBiFactorize returns a list of monic factors with |
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103 | /// multiplicity, the first element is the leading coefficient. |
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104 | inline |
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105 | CFFList |
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106 | ratBiFactorize (const CanonicalForm & G, ///< [in] a bivariate poly |
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107 | const Variable& v= Variable (1), ///< [in] algebraic variable |
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108 | bool substCheck= true ///< [in] enables substitute check |
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109 | ) |
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110 | { |
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111 | CFMap N; |
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112 | CanonicalForm F= compress (G, N); |
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113 | |
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114 | if (substCheck) |
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115 | { |
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116 | bool foundOne= false; |
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117 | int * substDegree= new int [F.level()]; |
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118 | for (int i= 1; i <= F.level(); i++) |
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119 | { |
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120 | substDegree[i-1]= substituteCheck (F, Variable (i)); |
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121 | if (substDegree [i-1] > 1) |
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122 | { |
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123 | foundOne= true; |
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124 | subst (F, F, substDegree[i-1], Variable (i)); |
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125 | } |
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126 | } |
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127 | if (foundOne) |
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128 | { |
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129 | CFFList result= ratBiFactorize (F, v, false); |
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130 | CFFList newResult, tmp; |
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131 | CanonicalForm tmp2; |
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132 | newResult.insert (result.getFirst()); |
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133 | result.removeFirst(); |
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134 | for (CFFListIterator i= result; i.hasItem(); i++) |
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135 | { |
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136 | tmp2= i.getItem().factor(); |
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137 | for (int j= 1; j <= F.level(); j++) |
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138 | { |
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139 | if (substDegree[j-1] > 1) |
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140 | tmp2= reverseSubst (tmp2, substDegree[j-1], Variable (j)); |
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141 | } |
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142 | tmp= ratBiFactorize (tmp2, v, false); |
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143 | tmp.removeFirst(); |
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144 | for (CFFListIterator j= tmp; j.hasItem(); j++) |
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145 | newResult.append (CFFactor (j.getItem().factor(), |
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146 | j.getItem().exp()*i.getItem().exp())); |
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147 | } |
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148 | decompress (newResult, N); |
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149 | delete [] substDegree; |
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150 | return newResult; |
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151 | } |
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152 | delete [] substDegree; |
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153 | } |
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154 | |
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155 | CanonicalForm LcF= Lc (F); |
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156 | CanonicalForm contentX= content (F, 1); |
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157 | CanonicalForm contentY= content (F, 2); |
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158 | F /= (contentX*contentY); |
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159 | CFFList contentXFactors, contentYFactors; |
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160 | if (v.level() != 1) |
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161 | { |
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162 | contentXFactors= factorize (contentX, v); |
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163 | contentYFactors= factorize (contentY, v); |
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164 | } |
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165 | else |
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166 | { |
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167 | contentXFactors= factorize (contentX); |
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168 | contentYFactors= factorize (contentY); |
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169 | } |
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170 | if (contentXFactors.getFirst().factor().inCoeffDomain()) |
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171 | contentXFactors.removeFirst(); |
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172 | if (contentYFactors.getFirst().factor().inCoeffDomain()) |
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173 | contentYFactors.removeFirst(); |
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174 | decompress (contentXFactors, N); |
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175 | decompress (contentYFactors, N); |
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176 | CFFList result, resultRoot; |
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177 | if (F.inCoeffDomain()) |
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178 | { |
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179 | result= Union (contentXFactors, contentYFactors); |
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180 | if (isOn (SW_RATIONAL)) |
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181 | { |
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182 | normalize (result); |
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183 | result.insert (CFFactor (LcF, 1)); |
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184 | } |
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185 | return result; |
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186 | } |
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187 | mat_ZZ M; |
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188 | vec_ZZ S; |
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189 | F= compress (F, M, S); |
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190 | CFFList sqrfFactors= sqrFree (F); |
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191 | for (CFFListIterator i= sqrfFactors; i.hasItem(); i++) |
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192 | { |
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193 | CFList tmp= ratBiSqrfFactorize (i.getItem().factor(), v); |
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194 | for (CFListIterator j= tmp; j.hasItem(); j++) |
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195 | { |
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196 | if (j.getItem().inCoeffDomain()) continue; |
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197 | result.append (CFFactor (N (decompress (j.getItem(), M, S)), i.getItem().exp())); |
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198 | } |
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199 | } |
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200 | result= Union (result, contentXFactors); |
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201 | result= Union (result, contentYFactors); |
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202 | if (isOn (SW_RATIONAL)) |
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203 | { |
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204 | normalize (result); |
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205 | result.insert (CFFactor (LcF, 1)); |
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206 | } |
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207 | return result; |
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208 | } |
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209 | |
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210 | #endif |
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211 | |
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212 | /// convert a CFFList to a CFList by dropping the multiplicity |
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213 | CFList conv (const CFFList& L ///< [in] a CFFList |
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214 | ); |
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215 | |
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216 | #endif |
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217 | |
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