Use double everywhere

Rationale:

- Speed of double and float is about the same (not on the hot path anyway)

- Double makes code prettier (no need to write 1.0f, just 1.0)

- Only practical advantage of float is to use less memory, but since we never
  store large arrays of double, we don't care.

No functional change.

src/misc.cpp

@@ -75,7 +75,7 @@ void dbg_print() {
 
   if (means[0])
       cerr << "Total " << means[0] << " Mean "
-           << (float)means[1] / means[0] << endl;
+           << (double)means[1] / means[0] << endl;
 }
 
 

src/notation.cpp

@@ -207,7 +207,7 @@ static string score_to_string(Value v) {
       s << "-#" << (VALUE_MATE + v) / 2;
 
   else
-      s << setprecision(2) << fixed << showpos << float(v) / PawnValueMg;
+      s << setprecision(2) << fixed << showpos << double(v) / PawnValueMg;
 
   return s.str();
 }

src/search.cpp

@@ -84,7 +84,7 @@ namespace {
 
   size_t PVSize, PVIdx;
   TimeManager TimeMgr;
-  float BestMoveChanges;
+  double BestMoveChanges;
   Value DrawValue[COLOR_NB];
   HistoryStats History;
   GainsStats Gains;
@@ -333,7 +333,7 @@ namespace {
     while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
     {
         // Age out PV variability metric
-        BestMoveChanges *= 0.8f;
+        BestMoveChanges *= 0.8;
 
         // Save last iteration's scores before first PV line is searched and all
         // the move scores but the (new) PV are set to -VALUE_INFINITE.

src/timeman.cpp

@@ -29,8 +29,8 @@ namespace {
   /// Constants
 
   const int MoveHorizon  = 50;    // Plan time management at most this many moves ahead
-  const float MaxRatio   = 7.0f;  // When in trouble, we can step over reserved time with this ratio
-  const float StealRatio = 0.33f; // However we must not steal time from remaining moves over this ratio
+  const double MaxRatio   = 7.0;  // When in trouble, we can step over reserved time with this ratio
+  const double StealRatio = 0.33; // However we must not steal time from remaining moves over this ratio
 
 
   // MoveImportance[] is based on naive statistical analysis of "how many games are still undecided
@@ -76,7 +76,7 @@ namespace {
 }
 
 
-void TimeManager::pv_instability(float bestMoveChanges) {
+void TimeManager::pv_instability(double bestMoveChanges) {
 
   unstablePVExtraTime = int(bestMoveChanges * optimumSearchTime);
 }
@@ -144,8 +144,8 @@ namespace {
   template<TimeType T>
   int remaining(int myTime, int movesToGo, int currentPly, int slowMover)
   {
-    const float TMaxRatio   = (T == OptimumTime ? 1 : MaxRatio);
-    const float TStealRatio = (T == OptimumTime ? 0 : StealRatio);
+    const double TMaxRatio   = (T == OptimumTime ? 1 : MaxRatio);
+    const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
 
     int thisMoveImportance = move_importance(currentPly) * slowMover / 100;
     int otherMovesImportance = 0;
@@ -153,8 +153,8 @@ namespace {
     for (int i = 1; i < movesToGo; ++i)
         otherMovesImportance += move_importance(currentPly + 2 * i);
 
-    float ratio1 = (TMaxRatio * thisMoveImportance) / float(TMaxRatio * thisMoveImportance + otherMovesImportance);
-    float ratio2 = (thisMoveImportance + TStealRatio * otherMovesImportance) / float(thisMoveImportance + otherMovesImportance);
+    double ratio1 = (TMaxRatio * thisMoveImportance) / double(TMaxRatio * thisMoveImportance + otherMovesImportance);
+    double ratio2 = (thisMoveImportance + TStealRatio * otherMovesImportance) / double(thisMoveImportance + otherMovesImportance);
 
     return int(floor(myTime * std::min(ratio1, ratio2)));
   }

src/timeman.h

@@ -26,7 +26,7 @@
 class TimeManager {
 public:
   void init(const Search::LimitsType& limits, int currentPly, Color us);
-  void pv_instability(float bestMoveChanges);
+  void pv_instability(double bestMoveChanges);
   int available_time() const { return optimumSearchTime + unstablePVExtraTime; }
   int maximum_time() const { return maximumSearchTime; }