Fix gauge determination. If we look upstream ( a > b ) we still have to compare the start value of our range against the gauge and not the end value. The start value is always the relevant value as we handle the direction by checking this against A or B of the gauge. Also: I will never compare doubles with == again. I will never compare doubles with == again. I will never compare doubles with == again. I will never compare doubles with == again. I will never compare doubles with == again.