code: public double getMin(double x, double y, double z)
  	{
  		double ret = Double.NaN;
  		if (!Double.isNaN(x))
  			ret = x;
  		if (!Double.isNaN(y))
  		{
  			if (!Double.isNaN(ret))
  				ret = Math.min(ret, y);
  			else
  				ret = y;
  		}
  		if (!Double.isNaN(z))
  		{
  			if (!Double.isNaN(ret))
  				ret = Math.min(ret, z);
  			else
  				ret = z;
  		}
  		return ret;
  	}
docs: Gets the minimum value of <code>x</code>, <code>y</code>, <code>z</code>.
  
  @param x the x
  @param y the y
  @param z the z
  @return <code>Double.NaN</code> if <code>x</code>, <code>y</code> and <code>z</code> are all three <code>Double.NaN</code>