dmm, to math
@dmm@mathstodon.xyz avatar

Here I tried to prove the Existence Theorem for Laplace Transforms. I don't know what the/a "conventional proof" looks like, but this is what I came up with.

A few of my notes on this and related topics are here: https://davidmeyer.github.io/qc/dirac_delta.pdf

As always, questions/comments/corrections/* greatly appreciated.

dmm,
@dmm@mathstodon.xyz avatar

@johncarlosbaez Not stressful, other than I worry I'm making you work to much.

I'm just learning all of this (learning things is what I like to do), so I appreciate not only your patience but also your time.

Thanks! --dmm

johncarlosbaez,
@johncarlosbaez@mathstodon.xyz avatar

@dmm - it's not work for me, it's fun!

gutenberg_org, to books
@gutenberg_org@mastodon.social avatar

French mathematician Abraham de Moivre was born in 1667.

He is best known for de Moivre's theorem, which links complex numbers and trigonometry, and for his work in the development of analytic geometry and the theory of equations. He published "The Doctrine of Chances" (1718) where he developed a formula for the normal approximation to the binomial distribution, now known as the de Moivre-Laplace theorem.

https://en.wikipedia.org/wiki/De_Moivre%27s_formula

https://en.wikipedia.org/wiki/De_Moivre%E2%80%93Laplace_theorem

The doctrine of chances: or, a method of calculating the probabilities of events in play, by A. de Moivre .... - London : printed for A. Millar, in the Strand, 1761. - [4], xi, [1], 348 p. ; 4º .

mkwadee, to animation
@mkwadee@mastodon.org.uk avatar

A couple of weeks ago, I posted an of a point on a circle generating a .

If you turn the curve "upside down", you get the . This curve provides the shortest travel time starting from one cusp to any other point on the curve for a ball rolling under uniform . It is always faster than the straight-line travel time.

Balls rolling under gravity on a cycloid and on straight lines inclined at various angles.

mkwadee,
@mkwadee@mastodon.org.uk avatar

This is an interesting problem in and exercised luminaries like and . I think the latter's use of the is a stroke of genius.

mkwadee,
@mkwadee@mastodon.org.uk avatar

Anyway, the took a bit of thought as it requires a bit of , some and is made a bit more tricky as the curve is multi-valued and so you need to treat different branches separately. The was produce with .

dmm, to math
@dmm@mathstodon.xyz avatar

Here's something I just learned: the lucky numbers of Euler.

Euler's "lucky" numbers are positive integers n such that for all integers k with 1 ≤ k < n, the polynomial k² − k + n produces a prime number.

Leonhard Euler published the polynomial k² − k + 41 which produces prime numbers for all integer values of k from 1 to 40.

Only 6 lucky numbers of Euler exist, namely 2, 3, 5, 11, 17 and 41 (sequence A014556 in the OEIS).

The Heegner numbers 7, 11, 19, 43, 67, 163, yield prime generating functions of Euler's form for 2, 3, 5, 11, 17, 41; these latter numbers are called lucky numbers of Euler by F. Le Lionnais.

h/t John Carlos Baez
(@johncarlosbaez) for pointing this out.

References

[1] "Lucky numbers of Euler", https://en.wikipedia.org/wiki/Lucky_numbers_of_Euler

[2] "Heegner number", https://en.wikipedia.org/wiki/Heegner_number

[3] "Heegner numbers: imaginary quadratic fields with unique factorization (or class number 1)", https://oeis.org/A003173

[4] "Euler's "Lucky" numbers: n such that m^2-m+n is prime for m=0..n-1", https://oeis.org/A003173

johncarlosbaez,
@johncarlosbaez@mathstodon.xyz avatar

@dmm - you came tantalizingly close to telling your readers how to get the sequence

7, 11, 19, 43, 67, 163

from the sequence

2, 3, 5, 11, 17, 41

but it's probably best to leave that as an easy puzzle for them! Of course, 𝑤h𝑦 𝑖𝑡 𝑤𝑜𝑟𝑘𝑠 is a much harder puzzle.

dmm, to math
@dmm@mathstodon.xyz avatar

The fascinating Heegner numbers [1] are so named for the amateur mathematician who proved Gauss' conjecture that the numbers {-1, -2, -3, -7, -11, -19, -43, -67,-163} are the only values of -d for which imaginary quadratic fields Q[√-d] are uniquely factorable into factors of the form a + b√-d (for a, b ∈ ℤ) (i.e., the field "splits" [2]). Today it is known that there are only nine Heegner numbers: -1, -2, -3, -7, -11, -19, -43, -67, and -163 [3].

Interestingly, the number 163 turns up in all kinds of surprising places, including the irrational constant e^{π√163} ≈ 262537412640768743.99999999999925... (≈ 2.6253741264×10^{17}), which is known as the Ramanujan Constant [4].

A few of my notes on this and related topics are here: https://davidmeyer.github.io/qc/galois_theory.pdf. As always, questions/comments/corrections/* greatly appreciated.

References

[1] "Heegner Number", https://mathworld.wolfram.com/HeegnerNumber.html

[2] "Splitting Field", https://mathworld.wolfram.com/SplittingField.html

[3] "Heegner numbers: imaginary quadratic fields with unique factorization (or class number 1).", https://oeis.org/A003173

[4] "Ramanujan Constant", https://mathworld.wolfram.com/RamanujanConstant.html

johncarlosbaez,
@johncarlosbaez@mathstodon.xyz avatar
dmm,
@dmm@mathstodon.xyz avatar

@johncarlosbaez "Lucky numbers of Euler" 🙂

https://en.wikipedia.org/wiki/Lucky_numbers_of_Euler

Very cool...

fractalkitty, (edited ) to math
@fractalkitty@mathstodon.xyz avatar

I am super excited for my friend Paulina's new book:

Mapmatics: A Mathematician's Guide to Navigating the World

If anyone in the media space is interested in doing a book review, please DM me, and I can provide information on how to get an advanced copy.

https://www.amazon.com/gp/product/0674294238

#math #mathbooks #mathematics #maps

MathOutLoud, to math
@MathOutLoud@mathstodon.xyz avatar

A nice viewer submitted problem today dealing with the range of values of a function. See my thought process and solution here:

https://youtu.be/KcCvTZDWbAU

LabPlot, to datascience
@LabPlot@floss.social avatar

Below is just a small sample of plots that were created with #lLabPlot.

@labplot

#LabPlot is a FREE, open source and cross-platform Data Visualization and Data Analysis software.

Would you like to share with us your plots made in LabPlot?

#DataAnalysis #DataScience #Data #DataViz #DataVisualization #Science #Statistics #Mathematics #Math #STEM #FOSS #FLOSS #OpenSource #KDE

quantarss, to mathematics
@quantarss@newsmast.social avatar
diffgeom, to mathematics
@diffgeom@mathstodon.xyz avatar
jcponcemath, to mathematics
@jcponcemath@mathstodon.xyz avatar
Metamere,
@Metamere@genart.social avatar

@jcponcemath That's a cool way to plot patterns like that! I made a sketch in that vein last year. Maybe I should try incorporating some of these.
https://openprocessing.org/sketch/1816143

Spiraling arcs that form interesting patterns. Slightly more coarse pattern, a bit wavy.

mattotcha, to physics
@mattotcha@mastodon.social avatar

New Research Sheds Light on the Forgotten 11th-Century Muslim Scientist That Fundamentally Transformed the History of Physics
https://scitechdaily.com/new-research-sheds-light-on-the-forgotten-11th-century-muslim-scientist-that-fundamentally-transformed-the-history-of-physics/

paysmaths, to mathematics French
@paysmaths@mathstodon.xyz avatar

"It seems to me now that mathematics is capable of an artistic excellence as great as that of any music, perhaps greater ; not because the pleasure it gives (although very pure) is comparable [...] to that of music [...]" – Bertrand Russell (1872–1970)

decompwlj, to mathematics
@decompwlj@mathstodon.xyz avatar
ramsey,
@ramsey@phpc.social avatar

@decompwlj I’m curious in what way was PHP used in creating these graphs?

micchiato, to Israel
@micchiato@mastodon.social avatar

“Since the beginning of #Israel’s war on #Gaza, academics in fields including #politics, #sociology, Japanese #literature, public #health, Latin American and Caribbean studies, Middle East and African studies, #mathematics, #education, and more have been fired, suspended, or removed from the classroom for pro-#Palestine, anti-Israel speech.”

https://theintercept.com/2024/05/16/university-college-professors-israel-palestine-firing/

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