def align(self, interval, stepSize):
print("plouf align")
intv = self.log10(interval)
x1 = QwtScaleArithmetic.floorEps(intv.minValue(), stepSize)
x2 = QwtScaleArithmetic.ceilEps(intv.maxValue(), stepSize)
return self.pow10(QwtDoubleInterval(x1, x2))
