
Cambridge University Press make their books free until May - DanBC
https://www.cambridge.org/core/what-we-publish/textbooks
======
asicsp
I was thinking on similar lines yesterday and today made the decision of
making all my ebooks free for the foreseeable future. I made bundles [0][1] so
that they can all be downloaded in one shot. There are five books - three of
them on regex (Ruby, Python, JavaScript) and two on cli tools (GNU grep and
ripgrep, GNU sed).

Currently working on GNU awk, which will take another month if I want to
include everything I had planned. Now, I'm thinking of releasing as drafts and
see how it goes.

I plan to release book markdown source as well in coming days. Already done
for Ruby [2]

[0] [https://leanpub.com/b/regex](https://leanpub.com/b/regex)

[1] [https://gumroad.com/l/regex](https://gumroad.com/l/regex)

[2]
[https://github.com/learnbyexample/Ruby_Regexp](https://github.com/learnbyexample/Ruby_Regexp)

~~~
supdatecron
This is really cool Sundeep, thanks for doing this! Question for you: what did
you use to draw the diagrams for the "Javascript Regex" book, such as on the
cover? Thanks!

~~~
asicsp
That is known as railroad diagrams and provided by sites such as regulex[0]
(which I used for js cover) and debuggex [1]. I've also mentioned it in
acknowledgements within the book.

[0] [https://jex.im/regulex](https://jex.im/regulex)

[1] [https://www.debuggex.com/](https://www.debuggex.com/)

------
oh_ryan
My company, VitalSource, which bought my startup Verba did this good thing
too! We have over a 100k ebooks from top higher ed publishers (including CUP)
available for free (download to your phone or computer, or use online)! You
need an institutional email address from a 2- or 4-year non-profit semester
based institution. Only America right now but we’re working on international!
Check it out at [https://get.vitalsource.com/vitalsource-
helps](https://get.vitalsource.com/vitalsource-helps) or log in / create
account at
[https://bookshelf.vitalsource.com](https://bookshelf.vitalsource.com), where
you can download the apps too. Limited to seven titles per user, and you are
automatically opted-out of any marketing now or ever and we won’t share your
info with anyone. Enjoy and good luck to everyone, especially those whose
campuses have moved to online instruction and you maybe lost access to
physical books left behind, shared with a friend, or from the library!

~~~
khafra
> ...did this good thing too!

> _email address from a 2- or 4-year non-profit semester based institution >
> __Only in America > ___seven titles per user

Good for you, but that's significantly more asterixes than Cambridge's offer.
I'm not sure I know anybody who's eligible.

------
skissane
Not all books, only some.

I remember one of their books [1], it was available for free PDF download for
a few months. I downloaded the PDF, then later wanted to read it again and
discovered I'd somehow misplaced the PDF. And now it isn't available for free
download any more. I was hoping it might be included in this, but it isn't.

[1] [https://www.cambridge.org/core/elements/atheism-and-
agnostic...](https://www.cambridge.org/core/elements/atheism-and-
agnosticism/C0D61CA2D386696A43294D440B7F9C11)

~~~
lostinroutine
Here you go:
[https://b-ok.cc/book/5260524/55d50b](https://b-ok.cc/book/5260524/55d50b) .
Z-lib (above) and Libgen are usually my go-to if I'm not sure I want to (or
can't) purchase a book.

~~~
llvim
is this legal?

~~~
lalaland1125
No. But not all illegal things are immoral.

~~~
degski
Limiting the acquisition of knowledge to people with sufficient economic means
is immoral, because it means that more than half the worlds population has no
means to move forward, even if they are motivated and intelligent.

------
conjectures
If there's one to grab, it's Janes's Probability Theory: The Logic of Science.

[https://www.cambridge.org/core/books/probability-
theory/9CA0...](https://www.cambridge.org/core/books/probability-
theory/9CA08E224FF30123304E6D8935CF1A99)

~~~
conjectures
* Jaynes's

------
Psychlist
Is there a way to search just for things that are actually downloadable? My
first 20 choices are not and it's getting a bit boring.

~~~
baking
They are not downloadable. They are available for online viewing. Check the
"Only show content I have access to" box.

~~~
Psychlist
Ah, so it's pretty much useless unless you need access to them right now and
have the time to spend. Useful to know, if annoying.

~~~
dyu
To be fair, this is exactly CUP's intent.

------
rodolphoarruda
Their ebook reader sucks. You have to go back to the index to advance between
chapters. Bad UX, but that's for a reason.

~~~
mkl
Wow, thanks! That is really bad. I just spent several minutes unsuccessfully
trying to get past the front matter. There are also lots of weird text
positioning glitches in their SVG (!) version of the book pages.

------
Dahoon
"Free for viewing online for now" isn't exactly "making books free". More like
"hey you can look at my things for a bit if you'd like but I'll hold it and
tomorrow you gotta pay to see it".

~~~
loco5niner
Yes, but it is making them "free to access online during the coronavirus
outbreak". Don't look a gift horse in the mouth.

------
bichiliad
This is wonderful! Does anyone have any particular recommendations (in any
subject)?

~~~
ironmagma
Dynamics of Particles and Rigid Bodies by Anil Rao
[https://www.amazon.com/Dynamics-Particles-Rigid-Bodies-
Syste...](https://www.amazon.com/Dynamics-Particles-Rigid-Bodies-
Systematic/dp/0521187907/ref=nodl_)

Dr. Rao’s systematic approach to solving dynamics problems is consistent and
concise. He also has a companion set of lecture notes on YouTube. I remember
it as one of the most challenging but rewarding aspects of my engineering
school experience. All the principles are described mathematically in a
coordinate-free manner. You’ll learn to set up equations of rigid bodies and
constraints without all the guesswork and haphazard construction of
coordinates typically encountered in a physics textbook.

~~~
b215826
I haven't read the book, but looking at the contents I'm surprised that the
author hasn't introduced analytical mechanics anywhere in the book. This might
be a good introductory book if you haven't taken a mechanics course before,
but using Newton's laws for understanding the dynamics of particles and rigid
bodies is a _terrible_ idea.

> _All the principles are described mathematically in a coordinate-free
> manner._

Newton's laws aren't coordinate free, e.g., Newton's second law written in
polar coordinates would look different from Newton's laws in Cartesian
coordinates. But, Lagrange's equations are coordinate-system independent.

~~~
ironmagma
This is definitely not an introductory level book. On the contrary, I wouldn't
recommend it unless you've done at least Calc 3 since you'll need a strong
grasp of vectors and derivatives. Newton's laws say e.g. the net force on an
object (a Euclidean vector) is equal to its mass multiplied by its
acceleration (also a Euclidean vector). That in itself is entirely coordinate
free, sure it assumes that the vector is not a moment, but that's different
from dictating a particular coordinate system.

You are right to say that if you wanted to express those laws in different
coordinate systems, they would look different, but the key to this system is
in essence that you leave any kind of coordinate projections till the very end
(lazy evaluation, to put it in a computer science analogy), at which point
much of the math is simplified due to term reduction, or various projections
cancel each other out.

What is tempting to bring in from other materials is the notion that a vector
has coordinates, which as far as this philosophy is concerned, they don't. A
vector is the direction and magnitude per sé, devoid of the concept of an
origin or any particular unit vectors with which you could represent that
vector numerically. It's a mindfuck for sure, and it confused all the students
in the class for a solid 3 weeks; that's why it's great.

~~~
b215826
> _This is definitely not an introductory level book_

I disagree. I used Kleppner and Kolenkow as a freshman, and it has pretty much
the same content as this book, and I would consider Kleppner and Kolenkow to
be an introductory book. Sure, it's more advanced than more common freshmen
books like Halliday and Resnick, but it is still very elementary mechanics.
Newton's laws is just the tip of the iceberg that is mechanics. Most advanced
books, including upper-division undergraduate books, would at least introduce
analytical mechanics, whereas this book doesn't. If you want more advanced
treatments of mechanics you should look at Landau and Lifshitz, or Arnold, or
Marsden, or even Lanczos (the latter three making moderate to extensive use of
Riemannian geometry and can be daunting for that reason alone).

> _but the key to this system is in essence that you leave any kind of
> coordinate projections till the very end_

That is not the definition of coordinate invariance, at least as defined in
physics. Newton's laws aren't coordinate invariant because the acceleration
involves the second derivative of coordinate basis vectors, and that is zero
(or constant) only in very few coordinate systems, like Cartesian coordinates
for instance. Of course, the statement F = ma still holds true, but becomes
very cumbersome to use if, say non-orthogonal coordinate systems are used. As
a simple example, try finding the equation of motion of a particle constrained
on a smooth surface, say a paraboloid z = x^2 + y^2 in Cartesian coordinates
using Newton's laws. Of course, this problem can be solved using Newton's laws
by introducing Lagrange multipliers, but that essentially amounts to finding
the constraint force. But it would be much better if you could avoid finding
the constraint force altogether.

> _A vector is the direction and magnitude per sé, devoid of the concept of an
> origin or any particular unit vectors with which you could represent that
> vector numerically._

You're right that it is important to distinguish between the geometrical
meaning of polar vectors and their representations in a particular coordinate
system. It's even more confusing when axial-/pseudo-vectors, e.g., the cross
product of two polar vectors, are introduced since now they _do_ depend on the
handedness of the coordinate system used. And why should nature care about
handedness? (It actually does, but that's a story for another day.) And this
is precisely why analytical mechanics, which is an inherently geometrical
subject, was invented in the first place! All equations in analytical
mechanics are scalar equations and look the same irrespective of the
coordinates you use to describe the system.

~~~
ironmagma
If you have a bone to pick about the term “coordinate free”, I suggest you
take it up with Dr. Rao. I am just forwarding along the message, and making a
recommendation.

> try finding the equation of motion of a particle constrained on a smooth
> surface, say a paraboloid z = x^2 + y^2 in Cartesian coordinates using
> Newton's laws

The method described in this book makes this kind of problem very
straightforward.

> Newton's laws aren't coordinate invariant because the acceleration involves
> the second derivative of coordinate basis vectors

I find this very doubtful. The acceleration of an object in real life does not
change depending on how you measure its position. Why would expressing the
quantities in math be any different? I think you are making a false assumption
that any given vector necessarily has a numerical representation. For
instance, if gravity acts down, and there is an object of mass m with no other
forces on it, Newton’s law says that F = m * g. Since g is in the down
direction, F is also down. Note that both F and g have direction and magnitude
in this word problem even though there are no basis vectors to speak of and
thus no way we can represent any of this numerically without defining more
mathematical objects. What would your coordinates be? We don’t have an origin
and we only have one axis, not enough to construct a right handed system or
any 3D system. Sure, we could do it one dimensionally but we’re talking 3D
Euclidean space for the purposes of this book.

~~~
b215826
> _I find this very doubtful._

I'm sorry to say this, but I don't think you understand the meaning of
coordinate invariance. Coordinate invariance in physics means that if you go
from one set of coordinates, say (q1, q2, ..., qn) to (s1, s2, ..., sn), the
_form_ of the equations remain invariant (assuming the transformation is nice
and smooth). Newton's laws aren't invariant under a general coordinate
transformation of that sort, and this is precisely because the acceleration
involves the second derivatives of the basis vectors. E.g., Newton's laws when
expressed in polar coordinates would involve centrifugal and Coriolis terms,
which are absent in Cartesian coordinates. Equations in analytical mechanics
(e.g., Lagrange's or Hamilton's equations) are coordinate invariant however
[1].

> _The method described in this book makes this kind of problem very
> straightforward._

Perhaps we have different definitions of "straightforward", but most
physicists I know would not consider using Newton's laws in Cartesian
coordinates to find the equations of a particle constrained to move on a
smooth surface straightforward. At the very least, one should try to introduce
a local coordinate system on the surface. It can be done, no doubt, but it's
way more cumbersome than writing Lagrange's equations involving the
generalized coordinates on that surface.

> _Note that both F and g have direction and magnitude in this word problem
> even though there are no basis vectors to speak of and thus no way we can
> represent any of this numerically without defining more mathematical
> objects._

No one is claiming that Newton's laws are invalid in different coordinates! Of
course they are valid and F = ma still holds true. The invariance you're
talking about is the general invariance of equations involving (polar)
vectors. That's obvious since vectors are inherently geometrical objects. But
that is in no way the same thing as "coordinate invariance". I'm not sure how
the book defines "coordinate free", and I certainly don't have a bone to pick
with anyone. But perhaps also look at how physicists define coordinate
invariance, since after all it's something they've been doing for a while?

I still stand by the claim that this book is a pretty elementary one. Sure,
you might've learned new things from this book, and I can see how many people
would benefit from it. But if you think this is what counts for "advanced
mechanics", then you're very very mistaken.

[1]:
[https://www.physicspages.com/pdf/Shankar/Shankar%20Exercises...](https://www.physicspages.com/pdf/Shankar/Shankar%20Exercises%2002.07.08%20\(1-3\).pdf)

~~~
ironmagma
I never said it was advanced mechanics, what I said was it's not an
introductory book. You shouldn't give this to someone who's never taken a
physics course. It's written for use in vehicle and aeronautical/astronautical
dynamics and supposes a fairly developed understanding of coordinate systems
and vector math.

> Perhaps we have different definitions of "straightforward"

It is certainly more straightforward than Lagrange. You just set up the
constraints, which is done in two steps: (1) set up the kinematics, i.e.
setting the position equal to some parameterization of that curve (2) set up
the dynamics, i.e. express Newton's laws in terms of the same variables. After
that, you can perform any derivatives needed using the transport theorem and
set the kinematics and dynamics equal to each other using the common
variables.

> Coordinate invariance in physics means

Since I'm not invoking the phrase "coordinate invariant" here I don't know
what the deal is. All I said was that the concepts in this book express
various physical laws including friction, Hooke's, and gravitational without
use of coordinates. There is no X, Y, Z or 1, 2, 3 of the vectors in these
descriptions. Whether to you that means coordinate invariant, is another story
but ultimately irrelevant.

> I still stand by the claim that this book is a pretty elementary one

Considering you've spent all this time arguing that it's not straightforward
(it is), I really suggest you take a look. It's nonconventional and may change
your perspective if you really give it a chance.

~~~
b215826
> _Considering you 've spent all this time arguing that it's not
> straightforward (it is), I really suggest you take a look._

I just downloaded a copy of the book from LibGen. I change my original
assessment that it might be a good introductory book. In fact, now I think
that this is a _terrible_ book that reinvents the wheel in so many places, and
novices should avoid it since it teaches bad practices. E.g., look at Example
3-2 of the book where the task is to find the motion of the particle
constrained on a parabola y = r^2/2R (similar to the paraboloid example I
asked, but more easier since the constraint manifold is one-dimensional). The
solution of that problem (Eq. 3-105) is 4 pages of algebra! The Lagrangian for
the system expressed in terms of r is

    
    
      L = m/2*(1 + r^2/R^2)*v^2 - (mg/2R)*r^2,
    

v being dr/dt. Now, to find Eq. 3-105, which the author derives in 4 pages,
all it takes is to plug this Lagrangian into the Euler-Lagrange equations, and
answer pops out in 2-3 lines of algebra involving some very trivial partial
derivatives. Curiously, the author has also reinvented d'Alembert's principle
when he does this problem the second time in Example 3-9. I'm also surprised
that the author hasn't mentioned d'Alembert's principle (or virtual work for
that matter) -- something that engineers make extensive use of -- anywhere in
this book.

> _Since I 'm not invoking the phrase "coordinate invariant" here I don't know
> what the deal is._

You did mention that this book introduces mechanics in a coordinate-free
manner (which this book actually doesn't).

> _It 's nonconventional and may change your perspective if you really give it
> a chance._

It's not just unconventional, this book is filled with terrible examples and
techniques to solve problems and the author has reinvented the wheel in
several places. The reason you found this book challenging was because this
book chooses to do problems using the most contrived methods possible. In
fact, this is a book to show why one needs analytical mechanics.

~~~
ironmagma
> In fact, this is a book to show why one needs analytical mechanics

I don't think the goal of the book is to obviate more advanced courses. It
does well what it sets out to do, which is lay a foundation of dynamics.
Contrasting it with other dynamics books I've read through, this one is self-
consistent and much easier to follow the math on. Yes, the solutions are often
long-winded, but that is the cost you pay for having a system. Other books
like Introduction to Space Dynamics are very hand-wavey and not easy to check
your work or find where you made a mistake, not to mention you must pick your
coordinate systems very carefully and up front. Coordinate systems should not
dictate the physics; it should be the other way around.

Besides, this methodology is applicable to other circumstances beyond just
dynamics. The rigorous approach to dealing with reference frames and
coordinate systems is well applied to other fields like computer graphics,
regardless of whether Lagrangian is more well suited to mechanical
applications.

> coordinate-free manner

Yes, I said that, not coordinate invariant, and in fact my description was
deliberately as devoid of jargon as I could make it. It should be taken as
plain English.

> It's not just unconventional, this book is filled with terrible examples and
> techniques to solve problems

Considering Dr. Rao's successful tenure working at Draper as well as working
on NASA spacecraft and other military vehicles, plus running a vehicle
dynamics lab, I'm inclined to believe it has value beyond what you believe it
to. Though I would be interested to read your textbook when it comes out, and
I do appreciate the perspective.

~~~
b215826
> _Other books like Introduction to Space Dynamics are very hand-wavey...
> Coordinate systems should not dictate the physics; it should be the other
> way around._

It seems like you've not tried reading actual physics books written by real
physicists and have only purveyed books known to a handful of engineering
specialists, and have come to the conclusion that this is the best book for
learning mechanics. I also fail to see why specialists wouldn't want to make
use of methods that would make their lives easier and instead would want to
dredge through pages of pointless algebra.

> _The rigorous approach to dealing with reference frames and coordinate
> systems is well applied to other fields like computer graphics_

In most universities around the world such things are taught as part of a
standard vector calculus course or a mathematical methods course. You don't
need this book (or any mechanics book for that matter) to learn such things.

> _Though I would be interested to read your textbook when it comes out_

I'll ignore the snideness of your comment, but will suggest that it's perhaps
not a good idea to recommend/use books that take haphazard approaches for
solving standard problems (some that were solve almost three centuries ago).
In any case, my "textbook" would not look very different from the other 99% of
textbooks written on analytical mechanics. If you want a recommendation, pick
up Cornelius Lanczos's _The Variational Principles of Mechanics_ [1], which is
a real classic and a gem of a book.

[1] [https://www.amazon.com/Variational-Principles-Mechanics-
Dove...](https://www.amazon.com/Variational-Principles-Mechanics-Dover-
Physics/dp/0486650677)

~~~
ironmagma
> It seems like you've not tried reading actual physics books written by real
> physicists

I find it pretty baffling you think this is the inescapable conclusion. Of
course I've taken physics courses, that's where the frustration comes from.
Many physics and astronomy books are riddled with errors and that's almost
entirely down to how frequently they skip steps. Not only are 90% of
underclassman physics texts written lazily at best, when I got into Modern
Physics, half the answers in the back of the book were flat-out wrong, while
the example problems elided a third of the steps or neglected important edge
cases. The book was Tipler / Llewellyn by the way.

> You don't need this book

Apparently I did, considering that none of the other relevant courses I took
which included calcs 1 through 3, differential equations, linear algebra,
mechanics of materials taught this material. I'm sure it would've come up
again if I'd stuck with mechanical engineering but regardless the whole point
of recommending the book is to say "this has value" not to say "other things
do not have this value."

> haphazard approaches

Compared to the other books I've seen, this is one of the most verbose,
consistent, and generally anal-retentive approaches. It does not take
shortcuts, and its notation alone is refreshing considering its lack of
ambiguous styling aside from minor issue of the bold being used for tensors
and vectors. (On the whiteboard, this is resolved with a double-underline
being used for tensors and a single-underline for vectors). I would consider
most other physics textbooks to be the haphazard ones, and when you compare
the rate of errors in the text I have a strong suspicion those other books
have much higher rates on average.

Granted, I'm not a physicist and make no claims to be. Of course there is
truth out there to be found among the vast sea of physics textbooks, but from
my own experience and also that of someone I know well who is postgrad in
plasma physics, the textbooks are generally shit and to gain a correct
understanding you need to wade through multiple texts that are extremely
fragmented in both notation and correctness. So I'm not sure physics is the
gold standard here. I'm sure there's a good math textbook out there about
coordinate systems, but like I said, I didn't post here to say "everything
else is worthless."

~~~
b215826
> _The book was Tipler / Llewellyn by the way._

Ah, you're talking about lower-level-answers-at-the-back undergraduate books
in physics. Yes, most of them are shit, and it would be a futile task to learn
any real physics from them. Who was even talking about such books? Lol.

> _I would consider most other physics textbooks to be the haphazard ones, and
> when you compare the rate of errors in the text I have a strong suspicion
> those other books have much higher rates on average_

From your comments it's pretty apparent that you've not even looked into any
graduate-level or even upper-level undergrad physics books and the only
physics books you've read are overpriced freshmen/sophomore physics textbooks.
In any case, do you really think a book (series) like Landau and Lifshitz or
_The Feynman Lectures_ (which is actually freshman physics) has more errors
and typos compared to some obscure text in engineering with contrived methods
and reinvented wheels? Lol.

Anyway, there's no point in taking this argument further. It's unlikely that
either of us would change our viewpoints ;-)

~~~
ironmagma
> In any case, do you really think a book (series) like Landau and Lifshitz or
> The Feynman Lectures (which is actually freshman physics)

If you think that's the bible, it's on you to recommend it. What isn't okay is
saying that books written by "real physicists" are the correct ones, when
Tipler and Llewellyn (and the other authors I didn't mention) are that. It's
dipping into the No True Scotsman territory. Graduate studies is not the world
in general; of course people who are studying a topic in their graduate degree
program are going to be using textbooks of a higher calibre, but also at the
cost of being inaccessible. HN isn't that audience, and neither are 99% of
audiences.

------
linker3000
John Wiley and Sons did similar a few weeks back for coronavirus-related
research publications in the Wiley Online Library:

[https://novel-coronavirus.onlinelibrary.wiley.com/](https://novel-
coronavirus.onlinelibrary.wiley.com/)

Disclaimer: Works for Wiley (UK)

------
WalterBright
Thank you! Very nice, and appreciated.

Nit: some of the text displayed overlaps other text (I'm using Chrome)
especially when displaying math, making it hard to read.

------
flocial
I wonder how long it'll take for someone to release a scraper to compile epubs
from this.

~~~
dependenttypes
Pretty sure that you could find them on libgen for ages.

------
rikelmens
And... not free to download for everyone anymore.

~~~
actualdc1
I wonder what they meant by "reported misuse?"

------
Habeebvet2020
Merk veterinary manual book

------
ImaCake
There's always libgen if the book you want is behind a paywall. Like it's
cousin scihub, it is very easy to use, fast, and has most of the books you
could possibly need. Considering the awful practices of most scientific
publishers, I have no problems with illegally downloading textbooks.

