wifi: remove Log2 function

Standard log2 is already used in wifi module anyway

src/wifi/model/wifi-utils.cc

@@ -28,13 +28,6 @@
 
 namespace ns3 {
 
-double
-Log2 (double val)
-{
-  return std::log (val) / std::log (2.0);
-}
-
-
 double
 DbToRatio (double dB)
 {

src/wifi/model/wifi-utils.h

@@ -30,14 +30,6 @@ class WifiMode;
 class Packet;
 class Time;
 
-/**
- * Return the logarithm of the given value to base 2.
- *
- * \param val
- *
- * \return the logarithm of val to base 2.
- */
-double Log2 (double val);
 /**
  * Convert from dBm to Watts.
  *

src/wifi/model/yans-error-rate-model.cc

@@ -62,10 +62,10 @@ YansErrorRateModel::GetQamBer (double snr, unsigned int m, uint32_t signalSpread
 {
   NS_LOG_FUNCTION (this << snr << m << signalSpread << phyRate);
   double EbNo = snr * signalSpread / phyRate;
-  double z = std::sqrt ((1.5 * Log2 (m) * EbNo) / (m - 1.0));
+  double z = std::sqrt ((1.5 * log2 (m) * EbNo) / (m - 1.0));
   double z1 = ((1.0 - 1.0 / std::sqrt (m)) * erfc (z));
   double z2 = 1 - std::pow ((1 - z1), 2);
-  double ber = z2 / Log2 (m);
+  double ber = z2 / log2 (m);
   NS_LOG_INFO ("Qam m=" << m << " rate=" << phyRate << " snr=" << snr << " ber=" << ber);
   return ber;
 }