David Bookstaber @davidbookstaber - Tumblr Blog

Where do trading profits come from? Three services: liquidity, information, and insurance. If you're not selling one of them when you trade, you're buying them.

Streaming Real-Time Market Data into Excel: Why RTD Beats an API for Analysts

An analyst doesn’t so much use Excel as live in it. The spreadsheet is where the models, the risk, and the intuition already sit. So when “get live market data into your model” turns into “learn our REST API, manage an auth token, write a polling loop, and reshape JSON,” the work has quietly moved out of the environment where you’re fluent and into one where you aren’t. I ran a live trading…

Early Memories

My body was born 50 years ago. I know this not only because my parents told me, but also because the government decided its business includes tracking and certifying exactly when, where, and of whom people are born. My body bears the scars and wear of 50 years of life. The first half of that period it was growing. Then it stopped growing and started down a predictable path of degeneration.…

Coding Agents Grow Up

For years, programming something new followed a predictable, exhausting rhythm: write some code, hit a wall, and then disappear into a forest of documentation and StackOverflow tabs to find the trick to get it working. In 2025, that era ended for me. Today, AI code assistants take so much drudgery out of development and debugging that the work has become mostly gratifying and rarely frustrating…

#AI Coding #GitHub Copilot

The Submission Trap

I’ve been posting more at Substack recently. Today’s post was a particularly long look at how some of the asymmetric protections for U.S. law enforcement officers (LEOs) have jeopardized citizens who should be wary of criminals masquerading as police. “The Submission Trap” is the current legal reality in America where you are more likely than ever to be assaulted by non-uniformed LEOs who are…

Chronograph Bias: True SD is Probably Higher

Standard Deviation Corrector Corrects bias in sample SD displayed by a chronograph.(Valid for all Normally distributed variables, like muzzle velocity.) Shots (n): Reported SD: Calculate Corrected SD Copy Result If you spend time on shooting forums or Instagram, you’ve seen the photos: A chronograph screen proudly displaying a Standard Deviation (SD) of muzzle velocity under 5 fps. A caption…

#Chronograph SD accuracy #Confidence Interval on estimated Standard Deviation #LabRadar SD Bias #MagnetoSpeed SD accuracy #SD vs ES #Unbiased Standard Deviation

Ad Fad: Food made with ... real food?

This half-page advertisement in Costco’s magazine for a nutritional supplement highlights that it’s “Powered by Real Food.” I don’t understand the market niche this is trying to fill. Are there people who can’t obtain or consume real food, so they turn to a pricey oral supplement that’s powered by real food? And pushing it further, in the same issue is the following half-page ad for food made…

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2025: The End of the Human Polymath

Born in 1976, I was just early enough to taste pre-internet life. In grade school, on a dial-up 1200baud modem and IBM PC, I was ahead of the curve in actually connecting to primordial pieces of the internet, though they didn’t have a lot of utility outside of academic collaboration. I grew up with a physical encyclopedia at home – the 22 volumes of the 1987 World Book Encyclopedia took up more…

Probability & Ballistics Ch1-3

I had hoped to publish this complete book in 2025. My current draft is over 55,000 words, painstakingly laid out over 155 pages with more than 100 figures. But it deserves another revision; I haven’t touched it since May; and at this rate I may not get around to finishing it before AI can do a better job. So here are the first three chapters, and anyone who wants to read more should let me know!

#Book

Adobe's Protection Racket

I just burned more than a day migrating my primary work computer from a machine running Windows 10 to a newer one running Windows 11. Not because I wanted to. Not because Win11 offers me anything I actually want (so far I hate every UI change from Win10). But because Microsoft has decided to end support for Win10 while preventing Win11 from running on older CPUs. And like everyone else whose work…

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#Boycott Adobe

Charmin quietly cuts roll size by 10%

Did they think we wouldn’t notice? Newer Charmin toilet paper rolls (left) are 10″ less wide but same diameter New Charmin toilet paper rolls are 4″ wide. Historically toilet paper has been sold in rolls that are 4.5″ wide. Did they make up for the cuts in length? The new rolls are advertised as having 231 sheets per roll, vs 213 for the previous size. But each new sheet is also 10% shorter.…

#inflation

Hot and cold running water? Not in Phoenix!

During summer in Phoenix we don’t have luxuries like hot and cold running water. Instead we have hot and hotter water. This photo shows me measuring the “cold” tap’s water emerging at 102°F: “Cold” tap water is 102°F If you haven’t run water recently you might enjoy a few moments of water as cold as the indoor air. But during summer the water supplied by the city routinely breaks 100°F. Is…

Slant: Ballistic solutions for aerial targets

As Russia continues to rain terror across Ukraine with kamikaze drones, I have been working overtime to upgrade the open-source ballistic calculator py_ballisticcalc to handle aerial targets. There will never be enough anti-aircraft defenses to cover a country that large, with an attacker who can send drones across any point in a border more than 1,400 miles long. But maybe we can save lives by…

Review: The Handmaid's Tale

Since its debut in 2017, The Handmaid’s Tale has offered an uncanny look at a society that descends — almost seamlessly — into theocratic totalitarianism. Adapted from Margaret Atwood’s 1985 novel, the Hulu series finds fresh horror not in the invention of new dystopias but in the recreation of real-world repression. When Atwood wrote her novel, the most salient examples may have been Soviet-era…

From https://www.thediff.co/archive/longreads-open-thread-126 regarding cheating with LLMs, Byrne Hobart writes: One question that comes up in this is: what do the students, and the professors, think they're actually doing here? When systems can be gamed, it's worth asking what the system is trying to accomplish. In some domains, people are perfectly aware of this: chess players know that computers can beat them, but that winning is not the only point of chess; weightlifters realize that pulleys would make the deadlift a lot easier. The outcome is a proxy, not the end goal, so it's worthwhile to ask: if gpt-4o can write plenty of grammatically-correct sentences, summarize texts, write snippets of code, etc., why exactly is society devoting so many nice campuses and talented teachers to the project of teaching people to replicate the outputs of a cheap consumer product? And, if students aren't doing the work and professors can't tell the difference, what's the resulting credential really worth?

Light Interaction App

Check out this nifty little touch-screen-compatible, WebGL-powered application. To test out the latest AI, I added Github Copilot to VSCode and asked it to build a simple web application that lets the user move three radiant lights (red, green, and blue) around a screen to see how adding colors works. (For example, if the three colors are right on top of each other it looks like a single white…

Word of the day: Gyming

#chinglish

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David Bookstaber