1 | /* Copyright 1997 Michael Messollen. All rights reserved. */ |
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2 | //////////////////////////////////////////////////////////// |
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3 | // $Id: homogfactor.cc,v 1.11 2008-04-09 09:41:48 Singular Exp $ |
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4 | //////////////////////////////////////////////////////////// |
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5 | // FACTORY - Includes |
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6 | #include <factory.h> |
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7 | #ifdef HAVE_IOSTREAM |
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8 | #include <iostream> |
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9 | #define OSTREAM std::ostream |
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10 | #define ISTREAM std::istream |
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11 | #define CERR std::cerr |
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12 | #define CIN std::cin |
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13 | #elif defined(HAVE_IOSTREAM_H) |
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14 | #include <iostream.h> |
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15 | #define OSTREAM ostream |
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16 | #define ISTREAM istream |
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17 | #define CERR cerr |
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18 | #define CIN cin |
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19 | #endif |
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20 | |
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21 | // Factor - Includes |
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22 | #include "tmpl_inst.h" |
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23 | #include "Factor.h" |
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24 | // some CC's need it: |
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25 | #include "homogfactor.h" |
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26 | |
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27 | void out_cf(char *s1,const CanonicalForm &f,char *s2); |
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28 | |
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29 | CFFList Factorize2(CanonicalForm F, const CanonicalForm & minpoly ); |
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30 | |
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31 | #ifdef HFACTORDEBUG |
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32 | # define DEBUGOUTPUT |
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33 | #else |
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34 | # undef DEBUGOUTPUT |
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35 | #endif |
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36 | |
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37 | #include "debug.h" |
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38 | #include "timing.h" |
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39 | TIMING_DEFINE_PRINT(hfactorize_time); |
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40 | |
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41 | #if 0 |
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42 | /////////////////////////////////////////////////////////////// |
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43 | // get_Terms: Split the polynomial in the containing terms. // |
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44 | // getTerms: the real work is done here. // |
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45 | /////////////////////////////////////////////////////////////// |
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46 | static void |
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47 | getTerms( const CanonicalForm & f, const CanonicalForm & t, CFList & result ){ |
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48 | |
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49 | if ( getNumVars(f) == 0 ) result.append(f*t); |
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50 | else{ |
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51 | Variable x(level(f)); |
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52 | for ( CFIterator i=f; i.hasTerms(); i++ ) |
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53 | getTerms( i.coeff(), t*power(x,i.exp()), result); |
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54 | } |
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55 | } |
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56 | |
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57 | CFList |
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58 | get_Terms( const CanonicalForm & f ){ |
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59 | CFList result,dummy,dummy2; |
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60 | CFIterator i; |
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61 | CFListIterator j; |
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62 | |
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63 | if ( getNumVars(f) == 0 ) result.append(f); |
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64 | else{ |
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65 | Variable _x(level(f)); |
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66 | for ( i=f; i.hasTerms(); i++ ){ |
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67 | getTerms(i.coeff(), 1, dummy); |
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68 | for ( j=dummy; j.hasItem(); j++ ) |
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69 | result.append(j.getItem() * power(_x, i.exp())); |
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70 | |
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71 | dummy= dummy2; // have to initalize new |
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72 | } |
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73 | } |
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74 | return result; |
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75 | } |
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76 | #endif |
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77 | |
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78 | #if 0 |
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79 | /////////////////////////////////////////////////////////////// |
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80 | // is_homogeneous returns 1 iff f is homogeneous, 0 otherwise// |
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81 | /////////////////////////////////////////////////////////////// |
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82 | bool |
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83 | is_homogeneous( const CanonicalForm & f){ |
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84 | CFList termlist= get_Terms(f); |
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85 | CFListIterator i; |
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86 | int deg= totaldegree(termlist.getFirst()); |
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87 | |
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88 | for ( i=termlist; i.hasItem(); i++ ) |
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89 | if ( totaldegree(i.getItem()) != deg ) return 0; |
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90 | return 1; |
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91 | // now: return f.isHomogeneous(); |
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92 | } |
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93 | #endif |
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94 | |
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95 | #if 0 |
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96 | /////////////////////////////////////////////////////////////// |
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97 | // get_max_degree_Variable returns Variable with // |
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98 | // highest degree. We assume f is *not* a constant! // |
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99 | /////////////////////////////////////////////////////////////// |
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100 | static Variable |
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101 | get_max_degree_Variable(const CanonicalForm & f){ |
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102 | ASSERT( ( ! f.inCoeffDomain() ), "no constants" ); |
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103 | int max=0, maxlevel=0, n=level(f); |
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104 | for ( int i=1; i<=n; i++ ) |
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105 | if (degree(f,Variable(i)) >= max) { |
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106 | max= degree(f,Variable(i)); maxlevel= i; |
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107 | } |
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108 | return Variable(maxlevel); |
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109 | } |
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110 | #endif |
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111 | |
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112 | #if 0 |
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113 | /////////////////////////////////////////////////////////////// |
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114 | // homogenize homogenizes f with Variable x // |
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115 | /////////////////////////////////////////////////////////////// |
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116 | static CanonicalForm |
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117 | homogenize( const CanonicalForm & f, const Variable & x){ |
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118 | CFList Newlist, Termlist= get_Terms(f); |
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119 | int maxdeg=totaldegree(f), deg; |
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120 | CFListIterator i; |
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121 | CanonicalForm elem, result=f.genZero(); |
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122 | |
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123 | for (i=Termlist; i.hasItem(); i++){ |
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124 | elem= i.getItem(); |
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125 | deg = totaldegree(elem); |
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126 | if ( deg < maxdeg ) |
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127 | Newlist.append(elem * power(x,maxdeg-deg)); |
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128 | else |
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129 | Newlist.append(elem); |
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130 | } |
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131 | for (i=Newlist; i.hasItem(); i++) // rebuild |
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132 | result += i.getItem(); |
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133 | |
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134 | return result; |
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135 | } |
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136 | #endif |
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137 | |
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138 | // we assume g is square-free |
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139 | CFFList |
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140 | HomogFactor( const CanonicalForm & g, const CanonicalForm & minpoly, const int Mainvar ) |
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141 | { |
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142 | DEBINCLEVEL(CERR, "HomogFactor"); |
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143 | Variable xn = get_max_degree_Variable(g); |
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144 | //out_cf("HomogFactor:",g,"\n"); |
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145 | int d_xn = degree(g,xn); |
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146 | CanonicalForm F = g(1,xn); |
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147 | |
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148 | DEBOUTLN(CERR, "xn= ", xn); |
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149 | DEBOUTLN(CERR, "d_xn= ", d_xn); |
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150 | DEBOUTLN(CERR, "F= ", F); |
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151 | //out_cf("HomogFactor:subst ",F,"\n"); |
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152 | |
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153 | // should we do this for low degree polys g ? e.g. quadratic? |
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154 | // |
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155 | CFFList Intermediatelist; |
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156 | CFFList Homoglist; |
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157 | CFFListIterator j; |
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158 | if ( getCharacteristic() > 0 ) |
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159 | { |
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160 | CFMap n; |
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161 | if (minpoly.isZero()) |
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162 | Intermediatelist = Factorize(compress(F,n), 1); |
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163 | else |
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164 | Intermediatelist = Factorized(compress(F,n), minpoly, Mainvar); |
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165 | for ( j=Intermediatelist; j.hasItem(); j++ ) |
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166 | Homoglist.append(CFFactor( n(j.getItem().factor()), j.getItem().exp()) ); |
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167 | } |
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168 | else |
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169 | { |
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170 | if (minpoly.isZero()) |
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171 | Homoglist = factorize(F); |
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172 | else |
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173 | Homoglist = Factorize2(F,minpoly); |
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174 | } |
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175 | // Now we have uncompressed factors in Homoglist |
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176 | DEBOUTLN(CERR, "F factors as: ", Homoglist); |
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177 | CFFList Unhomoglist; |
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178 | CanonicalForm unhomogelem; |
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179 | if ((!(minpoly.isZero())) &&(getCharacteristic() == 0) ) |
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180 | { |
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181 | for ( j=Homoglist; j.hasItem(); j++ ) |
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182 | { |
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183 | // assume that minpoly.level() < level of all "real" variables of g |
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184 | DEBOUTLN(CERR, "Homogenizing ",j.getItem().factor()); |
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185 | unhomogelem= homogenize(j.getItem().factor(),xn, |
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186 | Variable(minpoly.level()+1),g.mvar()); |
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187 | DEBOUTLN(CERR, " that is ", unhomogelem); |
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188 | Unhomoglist.append(CFFactor(unhomogelem,j.getItem().exp())); |
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189 | d_xn -= degree(unhomogelem,xn)*j.getItem().exp(); |
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190 | } |
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191 | } |
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192 | else |
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193 | { |
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194 | for ( j=Homoglist; j.hasItem(); j++ ) |
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195 | { |
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196 | DEBOUTLN(CERR, "Homogenizing ",j.getItem().factor()); |
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197 | unhomogelem= homogenize(j.getItem().factor(),xn); |
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198 | DEBOUTLN(CERR, " that is ", unhomogelem); |
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199 | //out_cf("unhomogelem:",unhomogelem,"\n"); |
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200 | Unhomoglist.append(CFFactor(unhomogelem,j.getItem().exp())); |
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201 | d_xn -= degree(unhomogelem,xn)*j.getItem().exp(); |
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202 | } |
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203 | } |
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204 | DEBOUTLN(CERR, "Power of xn to append is ", d_xn); |
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205 | if ( d_xn != 0 ) // have to append xn^(d_xn) |
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206 | Unhomoglist.append(CFFactor(CanonicalForm(xn),d_xn)); |
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207 | |
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208 | DEBDECLEVEL(CERR, "HomogFactor"); |
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209 | return Unhomoglist; |
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210 | } |
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211 | |
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212 | /* |
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213 | $Log: not supported by cvs2svn $ |
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214 | Revision 1.10 2008/04/08 16:19:10 Singular |
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215 | *hannes: removed rcsid |
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216 | |
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217 | Revision 1.9 2008/03/18 17:46:16 Singular |
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218 | *hannes: gcc 4.2 |
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219 | |
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220 | Revision 1.8 2007/10/25 14:45:41 Singular |
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221 | *hannes: homgfactor for alg.ext of Q |
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222 | |
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223 | Revision 1.7 2006/05/16 14:46:50 Singular |
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224 | *hannes: gcc 4.1 fixes |
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225 | |
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226 | Revision 1.6 2005/12/09 08:36:11 Singular |
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227 | *hannes: stuff for homog. polys ->factory |
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228 | |
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229 | Revision 1.5 2005/12/05 15:47:32 Singular |
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230 | *hannes: is_homogeneous -> factory: isHomogeneous |
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231 | |
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232 | Revision 1.4 2002/08/19 11:11:34 Singular |
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233 | * hannes/pfister: alg_gcd etc. |
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234 | |
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235 | Revision 1.3 1997/09/12 07:19:57 Singular |
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236 | * hannes/michael: libfac-0.3.0 |
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237 | |
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238 | Revision 1.2 1997/04/25 22:35:20 michael |
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239 | changed cerr and cout messages for use with Singular |
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240 | Version for libfac-0.2.1 |
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241 | |
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242 | Revision 1.1 1997/01/17 05:05:48 michael |
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243 | Initial revision |
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244 | |
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245 | */ |
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