Loss function

L(x,y,y^)L(x, y, \widehat{y})

The amount of utility lost py predicting y^\hat{y} instead of yy. We can often also use L(y,y^)L(y, \hat{y}) when the loss is independent of xx.

A Deep Learning model can improve by changing the weights and biases values. To do this, the model needs to know how good it performs and therefore we need a metric that can measure this performance. Depending on the type of problem we want to solve with our DNN one of the following metrics might be a solution: