[HN Gopher] The Princeton Companion to Applied Mathematics
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       The Princeton Companion to Applied Mathematics
        
       Author : teleforce
       Score  : 180 points
       Date   : 2024-04-28 05:05 UTC (17 hours ago)
        
 (HTM) web link (nhigham.com)
 (TXT) w3m dump (nhigham.com)
        
       | tedheath123 wrote:
       | How should one use a book like this? Is it to get an overview of
       | a topic before diving in? I don't think I've ever learnt any
       | mathematics from reference works, so I'm curious as to their
       | intended audience.
        
         | simonjgreen wrote:
         | I'd say appreciation of background and inspiration. The preface
         | linked on the page does a good job of positioning it too.
         | 
         | http://assets.press.princeton.edu/chapters/p10592.pdf
        
         | bluenose69 wrote:
         | The historical notes are a great strength of this book. As for
         | learning the material, from what you've written, you would
         | likely be better off with the sort of books used in first and
         | second year university.
         | 
         | A way to find good ones is to look at some university webpages,
         | to see what books they use in 1-level and 2-level classes. (Of
         | course, start with 1-level.). Those textbooks will be more
         | expansive, with interesting diagrams, problem sets, and so
         | forth. And they will use fancy typesetting patterns, like
         | insets in boxes for subtopics, etc.
         | 
         | I suspect quite a few purchasers will be university teachers
         | who want to have this on their shelves, for when students come
         | by and ask for a book to borrow overnight to brush up on a
         | topic.
        
         | kayo_20211030 wrote:
         | I wouldn't use a book like this for foundational learning. It's
         | more a precis of existing information on a topic. Looking at
         | one of the entries for Numerical Weather Forecasting, it
         | presupposes at least a solidly-established understanding in
         | Applied Math or Math Physics. If you're approaching that topic
         | without a basic knowledge of what a divergence is, what
         | vorticity is, what a gravity wave is, or the difference between
         | implicit and explicit FD equations, etc. it's probably not
         | going to teach you much. But, if you do have the background
         | it's a great resource - a really super resource. It's a bit
         | like Wikipedia, I suppose. Super helpful at some level, but not
         | at others.
        
         | detourdog wrote:
         | I would read the table of contents and pick the most
         | intriguing/relevant topic and see if it's comprehensible and
         | relevant.
        
         | epgui wrote:
         | It's a great way of getting to know what the landscape of
         | mathematics looks like.
        
         | lemonwaterlime wrote:
         | You use it like a conceptual dictionary. Say you're reading a
         | paper or trying to implement some technology that uses a
         | mathematical concept you aren't familiar with (e.g. a
         | submanifold). You'd look up "submanifold" and see that it is "
         | subset of a manifold that is itself a manifold, but has smaller
         | dimension." Okay, that seems to fit the intuition of a
         | "sub"-something. But I don't know what a "manifold" is. So I'd
         | look that up.
         | 
         | "A manifold is a topological space that is locally Euclidean
         | (i.e., around every point, there is a neighborhood that is
         | topologically the same as the open unit ball in R^n)"
         | 
         | At this point, either you know what all of those words mean or
         | you don't. If you do, great! You're done. If not, you either
         | keep digging deeper into the various terms or you start
         | seriously considering reading one or more of the curated
         | reference books listed at the end of each entry.
         | 
         | Over time you develop the "mathematical maturity" that you
         | don't need to do a deep dive into the books and can mostly just
         | use the reference.
        
           | Tainnor wrote:
           | > At this point, either you know what all of those words mean
           | or you don't. If you do, great! You're done.
           | 
           | I'm not sure. I only have a rather rudimentary understanding
           | of topology, so I do understand the definition of a manifold
           | on a technical level, but I don't know any interesting
           | examples or theorems about them so it wouldn't be immediately
           | clear to me why something being a submanifold is worth
           | mentioning.
           | 
           | Similarly, I don't think that just reading the definition
           | really gives you a good understanding of groups. You probably
           | want to work through some examples of groups, and arguably,
           | the importance of groups doesn't really become clear until
           | you've encountered group actions.
        
         | kxyvr wrote:
         | Outside of the other suggestions in this thread, this book may
         | also be helpful to someone interested in studying applied
         | mathematics in college, but unsure of what that means either in
         | terms of topics or career. I've only flipped through the book,
         | but it seems to do a good job at giving a high level overview
         | of various topics and applications. If one were to like what
         | they see, then perhaps one should investigate further.
         | 
         | In a similar topic, if someone is considering a career in
         | mathematics, I like the book, "A Mathematician's Survival
         | Guide: Graduate School and Early Career Development." It
         | applies to both pure and applied mathematicians, but it does a
         | good job of walking through undergraduate studies all of the
         | way to being a professor. Not all mathematicians end up in the
         | professoriate, but the graduate school information is still
         | valuable.
        
         | Mathnerd314 wrote:
         | Wait until it is out of copyright and then import it wholesale
         | into Wikipedia. But honestly Wikipedia already has most of the
         | content.
        
       | dtquad wrote:
       | The most advanced math I had were the 1st and 2nd year
       | multivariable calculus and linear algebra courses in college.
       | 
       | I am interested in visualizations/simulations of physical systems
       | as a way to learn advanced math. Is there any books or resources
       | that take that approach?
        
         | bloqs wrote:
         | Brilliant.com
        
         | ericdfoley wrote:
         | Computational Science and Engineering by Gilbert Strang
        
         | kubielid wrote:
         | Absolutely love the book "Learn Physics with Functional
         | Programming".
         | 
         | Uses Haskell, and teaches it so knowing Haskell is an
         | unnecessary prerequisite, though familiarity with programming
         | in general would be very beneficial, and focuses on 2D and 3D
         | visualisation.
        
         | thechao wrote:
         | I recently bootstrapped myself from your level to algebraic
         | geometry -- enough to read an annotated version of Einstein's
         | paper. If I had to do it again, I'd just skip to the parts that
         | worked: (1) hit up Michael Penn on YT, but work all the
         | problems he works; and, (2) learn GA, I like MacDonald's
         | "Linear and Geometric Algebra". I'm going to be honest: unless
         | you _do_ the homework, you can 't learn the math.
         | 
         | I learned Penn because it's "real" (mainstream) math & lets you
         | read in the same language; I learned GA because it's designed
         | to proselytize to other mathematicians & deliberately presents
         | serous ideas in very approachable ways.
        
         | lagrange77 wrote:
         | Take a look at this playlist [0] by MathTheBeautiful. It says
         | it's about PDEs, but it starts with ODEs.
         | 
         | I think most differential equations courses are too focused on
         | symbolic solving techniques. To me, understanding a (physical)
         | system is mainly understanding the differential equation
         | (system) itself, not it's solution. MathTheBeautiful really
         | excels at this approach.
         | 
         | Solutions are of course important as well, but i think that's
         | what computers are for.
         | 
         | [0]
         | https://www.youtube.com/playlist?list=PLlXfTHzgMRUK56vbQgzCV...
        
         | photochemsyn wrote:
         | The next two steps beyond that are probably vector calculus and
         | complex analysis. Check out Herb Gross's classic chalkboard
         | lectures on the topic:
         | 
         | https://ocw.mit.edu/courses/res-18-008-calculus-revisited-co...
         | 
         | When looking into simulations of physical systems, you'll run
         | into partial differential equations, but be careful about
         | learning resources that don't put numerical methods front and
         | center. The article on Numerical Weather Prediction in the post
         | has a good description:
         | 
         | > "Analytical solution of the equations is impossible, so
         | approximate methods must be employed. We consider methods of
         | discretizing the spatial domain to reduce the PDEs to an
         | algebraic system and of advancing the solution in time."
         | 
         | Given Python's popularity in scientific computing, a lot of the
         | available materials on the topic are in that language, using
         | libraries like numpy and scipy a lot. I've been playing around
         | with custom ChatGPT here - you can construct a workflow that
         | takes a description of a common equation, generates the LaTex
         | expression for it, translates that to a sympy expression, and
         | then from that generate the numerical method code using numpy
         | and then the code to plot the behavior over a given range in
         | matplotlib. Bonkers, we're living in the future.
        
       | gautamcgoel wrote:
       | For those of you who don't know: this is a companion to the
       | Princeton Companion to Mathematics, which is excellent but
       | focuses mainly on pure math. Also, the editor of this new volume
       | was a highly respected applied mathematician named Nick Higham,
       | who sadly died a few months ago.
        
         | pvitz wrote:
         | Oh no... I used his work on nearest positive semidefinite
         | matrices and liked to read his blog. In my opinion, he was very
         | good in explaining his research.
        
           | abhgh wrote:
           | Thanks for mentioning that. It's a problem I occasionally
           | need to solve and based on your comment, I found this helpful
           | write up by Nick Higham [1].
           | 
           | [1] https://nhigham.com/2021/01/26/what-is-the-nearest-
           | positive-...
        
             | pvitz wrote:
             | In my case, I am applying this in the calibration of
             | instantaneous correlation matrices. His relevant papers can
             | be found at [0]. It was really helpful that he also
             | published MATLAB code of most of his algorithms.
             | 
             | [0] https://nhigham.com/correlation-matrices/
        
       | jimbokun wrote:
       | This seems like the perfect book to put on your bookshelf to make
       | people think you are smart.
        
         | kubielid wrote:
         | I joked at an estate sale once that everyone has 3 bookshelves:
         | the books they read, the books they want to read, and the books
         | they want other people to think they read.
        
           | DeepSeaTortoise wrote:
           | IMO very few things can beat rows upon rows of fancy second
           | hand hard cover folders.
        
         | flatline wrote:
         | In fairness this one's predecessor has some pretty accessible
         | articles that I've actually read. It's more like an
         | encyclopedia. Some things I have the background for, others not
         | so much.
        
         | detourdog wrote:
         | This is a really bad take. I went straight to the algebraic
         | geometry. I subject I'm very interested but have no math
         | training.
         | 
         | I found the explanation on the development linkages to be
         | intriguing. It described the historical context and the steps
         | of development one key ideas.
         | 
         | Calling curious people posers is off putting.
        
           | kubielid wrote:
           | I read it as a joke, fellow MIDI enthusiast.
        
       | mturmon wrote:
       | I'm an encyclopedia lover who works on a variety of applied math
       | problems as part of $dayjob at a national lab.
       | 
       | I thought the book might be fun to browse around in, so I
       | purchased it. I knew the companion book (...to Mathematics) had a
       | very good reputation.
       | 
       | It didn't work for me...long story short is, the articles were
       | written at too high a level of sophistication to serve as an
       | introduction for a curious outsider. It was more of what someone
       | in a nearby field might want to get up to speed on what is known,
       | when their background in "that kind of thing" is already quite
       | strong.
       | 
       | I was surprised for various reasons - I know Higham's technical
       | work, enjoy his blog, and I have a decent math background. (Of
       | course, he's the editor, not the author - it's an enormous book.)
       | 
       | Ah, well. Not every shoe has to fit.
        
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