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log2

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SurvivorTiger

SurvivorTiger

Programmer
Jul 9, 2002
265
US
Hi everyone,

How can i do log2(number) in C++ ?
i thought maybe it would be part of the math.h header file...but that didn't seem to work for me...but maybe i was implementing it wrong?!

Please help!

AIM: Survivertiger
 
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Code: 
inline double log2(double x)
{
  static const double xxx = 1.0/log(2.0);
  return log(x)*xxx;
}
 
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On some implementations ln is more efficient than log but you have to run a loop a few thousand times to find out.
 
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