What poor countries have to do to get richer Teach everyone English by 
Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16This is obviously the most efficient investment any non-English speaking country must do, because you need to know English to be able to learn from rich countries and innovate.
Further discussion at: Section "Having more than one natural language is bad for the world".
Specifies fixed values.
Can be used for elliptic partial differential equations and parabolic partial differential equations.
Numerical examples:
Specifies the derivative in a direction normal to the boundary.
Can be used for elliptic partial differential equations and parabolic partial differential equations.
Sets both a Dirichlet boundary condition and a Neumann boundary condition for a single part of the boundary.
Can be used for hyperbolic partial differential equations.
We understand intuitively that this imposes stricter requirements on solutions, which makes it easier to guarantee uniqueness, but also harder to have existence. TODO intuitively why hyperbolic need this extra level of restriction.
Ciro Santilli's hardware Park Tool FR-5.2 Cassette Lockring Tool by Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16 Ciro Santilli's hardware ELEGOO Upgraded Electronics Fun Kit by Ciro Santilli 37 Updated 2025-07-27
Ciro Santilli 37 Updated 2025-07-272022-10 ELEGOO Upgraded Electronics Fun Kit www.elegoo.com/products/elegoo-electronics-fun-kits-4-versions Manuals:
- Elegoo Breadboard power supply module MB‐V2:TODO center positive or center negative?Does not come with AC adapter, getting this one: www.amazon.co.uk/dp/B08ZN476FW output: DC 9V 1A Power Supply Adapter, Plug 5.5mm x 2.1mm, Center Positive,B rand: Security-01, input: AC 100-240V 50/60 Hz, Cable length: 1.8mParts list from the ZIP:
- resistors:
- 1n4007 General Purpose Rectifier
- 22pf 104 Ceramic Capacitor
- 4N35 optocoupler
- 74HC595 8-bit serial-in, serial or parallel-out shift register with output latches; 3-state
- Active buzzer
- Buttons
- CDS-55 Photoresistor
- Electrolytic Capacitor
- Focusens MF52D 103f 3950 thermistor. Beta value 25/50 Celcius: 3950. R_25: I measured 9.61 k Ohms. The number 103 they document as:These descriptions are weird, but ChatGPT has the theory that the first two digits are actual values, and the last is multiplier, so which makes 10k.
but I have no idea how that maps to 10 k Ohms. - PN2222 General Purpose Transistor
- Passive buzzer
- 3386p Bourns Precision Potentiometer - 1 103T: from 0 to 10k Ohms, measured with multimeter. According to the manual the "103" mean 10 k oms, which is consistent with our measurement. "P 103" is etched into the part.
- LEDs:
This is crap, became slow very fast. The battery is IMPOSSIBLE to remove!!! youtu.be/kO-RwIQ_i1w?t=162 Battery was 4.163V when thing wouldn't turn on anymore. But topbattery.co.uk/product/original-battery-for-tablet-lenovo-yoga-tab-3-yt3-x50fyt3-x50m-sl20076-2/ says it is 3.6V. What?
- Dell XPS 15 www.dell.com/en-uk/shop/laptops/12th-gen-intel/spd/xps-15-9520-laptop
- CPU: Intel Core i7-12700H (12th gen)
- Graphics: Nvidia GeForce RTX 3050 Ti
- RAM: 16GB DDR5. Can be upgrated to 32 or 64.
- Display: 15.6-inch 3.5K (3,456 x 2,160), 60Hz
- Storage: 1TB PCIe NVMe M.2 SSD. Can be upgraded to 2TB or 4TB.
- Weight: 1.96 kg
- Price in UK: £1,948.99
- Ubuntu: no
- Tom's guide battery life: 10-hours (web browsing) www.tomsguide.com/reviews/dell-xps-15-oled-2022-review-a-great-macbook-pro-alternative
- Dell XPS 13 www.dell.com/en-uk/shop/laptops/xps-13/spd/xps-13-9315-laptop
- Dell XPS 13 plus
- ThinkPad X1 Carbon Gen 11 (14" Intel) www.lenovo.com/gb/en/p/laptops/thinkpad/thinkpadx1/thinkpad-x1-carbon-gen-11-(14-inch-intel)/len101t0049
Ciro Santilli's hardware Seagate ST1000LM035-1RK1 1TB hard disk by Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-161TB.
www.disctech.com/Seagate-ST1000LM035-1TB-SATA-Hard-Drive 80 USD | web.archive.org/web/20181224201408/https://www.disctech.com/Seagate-ST1000LM035-1TB-SATA-Hard-Drive
www.seagate.com/www-content/datasheets/pdfs/mobile-hddDS1861-2-1603-en_US.pdf | web.archive.org/web/20181225095438/https://www.seagate.com/www-content/datasheets/pdfs/mobile-hddDS1861-2-1603-en_US.pdf
sudo hdparm -Tt /dev/sda3 on Ubuntu 20.04:All those dedicated applied mathematicians languages are a waste of society's time, Ciro Santilli sure applied mathematicians are capable of writing a few extra braces in exchange for a sane general purpose language, we should instead just invest in good libraries with fast C bindings for those languages like NumPy where needed, and powerful mainlined integrated development environments.
And when Ciro Santilli see the closed source ones like MATLAB being used, it makes him lose all hope on humanity. Why. As of 2020. Why? In the 1980s, maybe. But in the 2020s?
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact