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comparison src/DLD-FUNCTIONS/rand.cc @ 14688:42edbe6f6a8d stable

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Fix bad two-arg call of randperm (bug #36535) * rand.cc (Frandperm): Rewrite algorithm for short_shuffle. Add another test.
author Jordi Gutiérrez Hermoso <jordigh@octave.org>
date Fri, 25 May 2012 11:24:02 -0400
parents 72c96de7a403
children 52c5fb67fa5f
comparison
equal deleted inserted replaced
14686:847ed7f603cf 14688:42edbe6f6a8d
1084 for (octave_idx_type i = 0; i < m; i++) 1084 for (octave_idx_type i = 0; i < m; i++)
1085 { 1085 {
1086 octave_idx_type k = i + 1086 octave_idx_type k = i +
1087 gnulib::floor (rvec[i] * (n - i)); 1087 gnulib::floor (rvec[i] * (n - i));
1088 1088
1089 if (map.find(k) == map.end()) 1089 //For shuffling first m entries, no need to use extra
1090 //storage
1091 if (k < m)
1090 { 1092 {
1091 map[k] = ivec[i]; 1093 std::swap (ivec[i], ivec[k]);
1092 ivec[i] = k;
1093 } 1094 }
1094 else 1095 else
1095 std::swap (ivec[i], map[k]); 1096 {
1096 1097 if (map.find (k) == map.end ())
1098 map[k] = k;
1099
1100 std::swap (ivec[i], map[k]);
1101 }
1097 } 1102 }
1098 } 1103 }
1099 else 1104 else
1100 { 1105 {
1101 1106
1124 1129
1125 return retval; 1130 return retval;
1126 } 1131 }
1127 1132
1128 /* 1133 /*
1129 %!assert(sort (randperm (20)),1:20) 1134 %!assert (sort (randperm (20)), 1:20)
1130 %!assert(length (randperm (20,10)), 10) 1135 %!assert (length (randperm (20,10)), 10)
1136
1137 %!test
1138 %! rand ("seed", 0);
1139 %! for i = 1:100
1140 %! p = randperm (305, 30);
1141 %! assert (length (unique (p)), 30);
1142 %! endfor
1131 */ 1143 */