Errata

Practical Linear Algebra for Data Science

Errata for Practical Linear Algebra for Data Science

Submit your own errata for this product.

The errata list is a list of errors and their corrections that were found after the product was released. If the error was corrected in a later version or reprint the date of the correction will be displayed in the column titled "Date Corrected".

The following errata were submitted by our customers and approved as valid errors by the author or editor.

Color key: Serious technical mistake Minor technical mistake Language or formatting error Typo Question Note Update

Version Location Description Submitted By Date submitted Date corrected
Page GLM in a Simple Example
32nd paragraph after figure 11-3

The values for the equation Xbeta = y, are switched. The design matrix X should have number of courses taken not life happiness. Same error is repeated when adding intercept.

Note from the Author or Editor:
Great catch! Indeed, the columns are swapped. The [25 54 21 80] and [4 12 3 14] should be swapped. This appears on pages 184 and 186. Fortunately, it is correct in the online code.

 Fakhry Khellah  Feb 10, 2023  Jul 14, 2023
Page 12
3rd paragraph

The code that implements equation 2-4 implements [4,5,6] as a row vector instead of a column vector (as it is presented in the equation). While the [10,20,30] vector is implemented as a column vector instead of a row vector (as it is presented in equation 2-4).

Note from the Author or Editor:
Great catch! Mathematically, it doesn't matter -- you technically cannot add a row and a column regardless of their order.

In Python, it does make a difference because one order is interpreted as broadcasting, as I show in the code. But it would be less confusing for the math and the code to match perfectly. I'll adjust the equation.

 Daniella Tola  Jan 29, 2024 
PDF
Page 30
Exercise 2-6

"Equation 2-8" is referenced in Exercise 2-6. This should be "Equation 2-7".

 Mike X Cohen
Mike X Cohen
 		 Jun 17, 2023  Jul 14, 2023
Page 45
3rd paragraph

In the paragraph starting with these lines "What linear weighted combination describes point p in set U? Well, the coefficients for the linear weighted combination of the three vectors in U could be (3, 0, 1) or (0, 1.5, 1) or…a bajillion other possibilities." The coefficients listed produce a point of p=(1,3) whereas the point p in the Figure 3-4 is p=(3,1).

Note from the Author or Editor:
Oh, great catch! The best fix here is to swap the rows of U, so the first row is 1,2,0 and the second row is 0,0,1

 Nadeem Ahmed  Jan 05, 2023  Jul 14, 2023
Page 87
1st equation on top of the page

On the left hand side of the equation on top, the elements in first column of the matrix is [3, 5, 1]. However, the elements next to lambda1 on the right side of equation is [1, 5, 1]. My understanding is these two parts should be the same (after all [1, 5, 1] is not in the column space of the matrix on the left).

Note from the Author or Editor:
Ah, that's a typo. Great catch! It should indeed be 3,5,1 in both cases.

 Daniel Xu  Dec 11, 2022  Jul 14, 2023
PDF
Page 106
4th summary point

The printed text says "There are four matrix spaces (column, row, null, left-null)"

The list of spaces should be "(column, row, null, right-null)"

 Mike X Cohen
Mike X Cohen
 		 Feb 14, 2023  Jul 14, 2023
PDF
Page 206
penultimate sentence in final paragraph

Exercise 12-1 has the following: "select only the data rows that have zero rainfall."
It should be "select only the data rows that have non-zero rainfall."

My apologies for that typo.

 Mike X Cohen
Mike X Cohen
 		 Jul 05, 2023  Jul 14, 2023
Page 230
after 2rd paragraph

The third equation

$(v_1+v_2)^TA(v_1+v_2)=(\lambda_1+\lambda_2)||(v_1+v_2)||^2$

does not hold,even for a symmetric matrix.

Note from the Author or Editor:
Good catch! I left out the eigenvector weight terms, which changes the equations slightly. I also expanded that paragraph to discuss the argument and that it's simplified for symmetric matrices.

 Anonymous  Jan 14, 2024 
Page 246
5rd paragraph and 6rd paragraph

5rd paragraph:

"the squared eigenvalues of AA^T are the singular values of A" is wrong, it should be “the eigenvalues of AA^T are the squares of the singular values of A”.

so in 6rd paragraph:
(1) singular values are nonnegative because squared numbers cannot be negative, (2) singular values are real-valued because symmetric matrices have real-valued eigenvalues

are wrong.

Singular values are real-valued because the eigenvalues of AA^T is nonnegative(positive semidefinite), they are square roots of the eigenvalues of AA^T.


Note from the Author or Editor:
Yes, you're correct, my apologies for the typos, and thanks for posting about it.

 Anonymous  Jan 16, 2024