public static float Log(float value, float newBase)
{
if (value < 0.0f ||
newBase < 0.0f ||
(value != 1.0f && newBase == 0.0f) ||
(value != 1.0f && newBase == float.PositiveInfinity) ||
XMath.IsNaN(value) ||
XMath.IsNaN(newBase) ||
newBase == 1.0f)
{
return(float.NaN);
}
if (value == 0.0f)
{
if (0.0f < newBase && newBase < 1.0f)
{
return(float.PositiveInfinity);
}
else if (newBase > 1.0f)
{
return(float.NegativeInfinity);
}
}
if (value == float.PositiveInfinity)
{
if (0.0f < newBase && newBase < 1.0f)
{
return(float.NegativeInfinity);
}
else if (newBase > 1.0f)
{
return(float.PositiveInfinity);
}
}
if (value == 1.0f && (newBase == 0.0f || newBase == float.PositiveInfinity))
{
return(0.0f);
}
return(XMath.Log(value) * XMath.Rcp(XMath.Log(newBase)));
}
public static double Log(double value, double newBase)
{
if (value < 0.0 ||
newBase < 0.0 ||
(value != 1.0 && newBase == 0.0) ||
(value != 1.0 && newBase == double.PositiveInfinity) ||
XMath.IsNaN(value) ||
XMath.IsNaN(newBase) ||
newBase == 1.0)
{
return(double.NaN);
}
if (value == 0.0)
{
if (0.0 < newBase && newBase < 1.0)
{
return(double.PositiveInfinity);
}
else if (newBase > 1.0)
{
return(double.NegativeInfinity);
}
}
if (value == double.PositiveInfinity)
{
if (0.0 < newBase && newBase < 1.0)
{
return(double.NegativeInfinity);
}
else if (newBase > 1.0)
{
return(double.PositiveInfinity);
}
}
if (value == 1.0 && (newBase == 0.0 || newBase == double.PositiveInfinity))
{
return(0.0);
}
return(XMath.Log(value) * XMath.Rcp(XMath.Log(newBase)));
}
public static float Log10(float value) => XMath.Log(value) * XMath.OneOverLn10;
static double Log(double x) => XMath.Log((float)x);