When you do this calculation purely numerically, its matrix vector multiplication.

当你用纯数值的方法计算时 它是矩阵向量的乘法。

You might notice that this looks a lot like matrix vector multiplication.

你可能注意到这看起来很像矩阵向量乘法。

You could even define this as matrix vector multiplication when you put the matrix on the left of the vector, like its a function.

你甚至可以把它定义为矩阵向量乘法当你把矩阵放在向量的左边 就像它是一个函数。

So surprisingly, matrix vector multiplication and taking a derivative, which at 1st seem like completely different animals, are both just really members of the same family.

所以令人惊讶的是 矩阵向量乘法和求导 乍一看完全不同的东西 实际上都是同一个家族的成员。

It's a little awkward to work with at 1st, because that left hand side represents matrix factor multiplication, but the right hand side here is scalar vector multiplication.

首先处理这个有点尴尬 因为左边表示矩阵因子的乘法 但右边是标量向量的乘法。

So let's start by rewriting that right hand side as some kind of matrix vector multiplication, using a matrix which has the effect of scaling any vector by a factor of lambda.

我们先把右边写成某种矩阵向量的乘法 用一个矩阵它的作用是将任意向量乘以的倍数。

The convention is to record the coordinates of where I had in j hat land as the columns of a matrix, and to define this, some of the scaled versions of those columns by x and y to be matrix vector multiplication.

惯例是记录我在jhat土地上的坐标作为矩阵的列 为了定义这个 这些列被x和y缩放的一些版本是矩阵向量的乘法。