Fix Gauss. elim.

Author: WrathfulSpatula

FindAFactor/_find_a_factor.cpp

@@ -896,8 +896,7 @@ struct Factorizer {
       for (size_t row = colPlus1; row < rows; ++row) {
         ++mRowIt;
         ++nRowIt;
-        const boost::dynamic_bitset<size_t> rowCopy = *mRowIt;
-        if (rowCopy[col]) {
+        if ((*mRowIt)[col]) {
           // Swapping matrix rows corresponds
           // with swapping factorized numbers.
           std::swap(*mColIt, *mRowIt);
@@ -906,44 +905,48 @@ struct Factorizer {
           // Mark this column as having a pivot.
           result.marks[col] = true;
 
-          // Pivot found, now eliminate entries in this column
-          const boost::dynamic_bitset<size_t> &cm = *mColIt;
-          const BigInteger &cn = *nColIt;
-          auto emRowIt = smoothNumberValues.begin();
-          auto enRowIt = smoothNumberKeys.begin();
-          const size_t maxLcv = std::min((size_t)CpuCount, rows);
-          for (size_t cpu = 0U; cpu < maxLcv; ++cpu) {
-            dispatch.dispatch([cpu, &cpuCount, &col, &rows, &cm, &cn, emRowIt, enRowIt]() -> bool {
-              // Notice that each thread updates rows with space increments of cpuCount,
-              // based on the same unchanged outer-loop row, and this covers the inner-loop set.
-              auto mrIt = emRowIt;
-              auto nrIt = enRowIt;
-              for (size_t row = cpu; ; row += cpuCount) {
-                boost::dynamic_bitset<size_t> &rm = *mrIt;
-                BigInteger &rn = *nrIt;
-                if ((row != col) && rm[col]) {
-                  // XOR-ing factorization rows
-                  // is like multiplying the numbers.
-                  rm ^= cm;
-                  rn *= cn;
-                }
-                if ((row + cpuCount) >= rows) {
-                  // This is the completion condition.
-                  return false;
-                }
-                // Every row advance is staggered according to cpuCount.
-                std::advance(mrIt, cpuCount);
-                std::advance(nrIt, cpuCount);
+          break;
+        }
+      }
+
+      if (result.marks[col]) {
+        // Pivot found, now eliminate entries in this column
+        const boost::dynamic_bitset<size_t> &cm = *mColIt;
+        const BigInteger &cn = *nColIt;
+        auto emRowIt = smoothNumberValues.begin();
+        auto enRowIt = smoothNumberKeys.begin();
+        const size_t maxLcv = std::min((size_t)CpuCount, rows);
+        for (size_t cpu = 0U; cpu < maxLcv; ++cpu) {
+          dispatch.dispatch([cpu, &cpuCount, &col, &rows, &cm, &cn, emRowIt, enRowIt]() -> bool {
+            // Notice that each thread updates rows with space increments of cpuCount,
+            // based on the same unchanged outer-loop row, and this covers the inner-loop set.
+            auto mrIt = emRowIt;
+            auto nrIt = enRowIt;
+            for (size_t row = cpu; ; row += cpuCount) {
+              boost::dynamic_bitset<size_t> &rm = *mrIt;
+              BigInteger &rn = *nrIt;
+              if ((row != col) && rm[col]) {
+                // XOR-ing factorization rows
+                // is like multiplying the numbers.
+                rm ^= cm;
+                rn *= cn;
               }
-              return false;
-            });
-            // Next inner-loop row (all at once by dispatch).
-            ++emRowIt;
-            ++enRowIt;
-          }
-          // All dispatched work must complete.
-          dispatch.finish();
+              if ((row + cpuCount) >= rows) {
+                // This is the completion condition.
+                return false;
+              }
+              // Every row advance is staggered according to cpuCount.
+              std::advance(mrIt, cpuCount);
+              std::advance(nrIt, cpuCount);
+            }
+            return false;
+          });
+          // Next inner-loop row (all at once by dispatch).
+          ++emRowIt;
+          ++enRowIt;
         }
+        // All dispatched work must complete.
+        dispatch.finish();
       }
 
       // Next outer-loop row