源范围【minX，maxX】到目标范围【minY，maxY】的指数变换；
double AbstractCalculator::expConvert(double x, double base, double minX, double maxX, double minY, double maxY)
double factor = (maxY - minY) / (log(maxX + base) - log(minX + base));
return (exp((x + factor * log(minX + base) - minY) / factor) - base);
}
源范围【minX，maxX】到目标范围【minY，maxY】的对数变换；变换效果为：两端向中间靠近；
{
double factor = (maxY - minY) / (log(maxX + base) - log(minX + base));
return (factor * (log(x + base) - log(minX + base)) + minY);
}