Least-squares methods work by minimising the sub of the squares of the differnce between the output of a model or system and its desired output. Examples include linear regression and backpropagation for neural networks. Similar methods can try to minimise the sum of the absolute errors, or the maximum error, but often squares are easier to work with mathematically.
Used in Chap. 7: pages 98, 104, 105; Chap. 8: page 116; Chap. 10: page 150
Also known as least squares estimate