I’veI've recently started reading a book about deep learning (machine learning). The book is titled “grokking"Grokking Deep Learning” byLearning" (by Andrew W Trask). The areas of confusing isIn chapter 3 pages(pages 44 and 45. It), it talks about multiplying vectors using dot product and elementwiseelement-wise multiplication. For instance, taking 3 scalar inputs (vector) and 3 vector weights (vectormatrix) and multiplying.
From my understanding, when multiplying vectors the size needs to be identical. The concept I’mI have a hard time understanding is multiplying vectors by a matrix. The book gives an example of an 1x4(vector) vector being multipledmultiplied by 4x3(matrix) matrix. The output is an 1x3 vector. ImI'm am confused because I assumed multiplying vector by matrix needs the same number of columns as well, but I have read that the matrixesmatrices need rows equal to the vectors columns.
This is confusing to me because ifIf I do not have an equal number of columns, how does my deep learning algorithm multiply each input in my vector by a corresponding weight?