Quadratic cost function ($C = \frac {(y-a)^2}{2}$) This is nice and simple, with the additional bonus that $C’ = y - a$ The loss grows exponentially, so a large error is treated a lot more harshly than a small error - this seems a good idea It’s very xenophobic, in that it will go out of its way to harm outliers The exponent will cause the loss to always be positive.
