Welcome to the Blog!
(stuff that doesn’t go anywhere else)

Dice games that let dice be dice

Ace-High Poker Dice
Aces can be high or low, so straights can be five, six, or ace high.
Relative probability of each hand (including full house and straight) is the same as that for cards.
Options include the house keeping its kept dice concealed to reduce the player’s considerable advantage.
When should you re-roll a pair?

Lucky Thirteen Blackjack Dice
Aces count as one or seven, and a blackjack is an ace and a six for a total of thirteen.
Blackjack pays 3:2; dealer must hit soft eleven.
Includes the basic strategy and win rate per hand.
Stand on hard eleven or soft twelve, except . . . .

annular eclipse
Annular eclipse of 10/14/2023
Beowawe, Nevada
annular eclipse


A Mouse Pointer Random Number Generator
Uses the mouse pointer to generate random numbers or characters. Passes the NIST Statistical Test Suite.


SMPTE  Film  Leader
An animated SVG image that simulates an old-style film leader. No reason . . . .

Print an image onto a glass so it appears rectilinear when viewed straight on.
The script uses a transformation which accounts for the conical or cylindrical shape of the glass, as the case may be.

(x, y) α θ s r

1000000107986132719 1000000107986132779
1000000107986132783 1000000107986132789
1000000107986132797 1000000107986132819
1000000107986132969 1000000107986132989
1000000107986133047 1000000107986133091
1000000107986133103 1000000107986133131
1000000107986133269 1000000107986133479
1000000107986133547 1000000107986133613
1000000107986133649 1000000107986133659
1000000107986133713 1000000107986133721
1000000107986133763 1000000107986133767
1000000107986133809 1000000107986133829
1000000107986133889 1000000107986133923
1000000107986133949 1000000107986133953
1000000107986133977 1000000107986134019
1000000107986134027 1000000107986134111

Thrilling JavaScript stuff

Calculate the billionth Fibonacci number in 22 seconds!
With a very simple fast doubling algorithm.
(Spoiler alert:  it has 208,987,640 digits.)

Use a bit array to calculate prime numbers above 1,000,000,000,000,000,000 in 60 seconds!
(starting with 1,000,000,000,000,000,003, of course.)

Afterimage color
Uses an afterimage to transform a black-and-white image into a color one.


SVG graphs, JavaScript calculus, and the circumference of an ellipse

SVG Graph(updated 7/16/2022)
SVG Graph is a script library that creates mathematical graphs with Cartesian, logarithmic, or polar coordinates. Shapes and text labels may be added using the actual graph coordinates, centered on the origin. One may pan and zoom the graph, and use the resulting coordinates to fine-tune the graph itself. Graphs may be saved as inline or external .svg files, or .png images.

JavaScript Calculus
Can you do calculus with JavaScript?

RC Clock Works

More clocks

Clock Chimes
Clock Chimes runs in the background to play quarter and hour chimes accurately.
It uses a web worker that runs in an operating system thread, independent of the browser.
The chime sounds are synthesized, keeping the document size small.

A simple SVG clock for your site.

Bond tools

Combining fixed-income securities with a managed account
Fixed-income securities (such as bonds held to maturity, or annuities) may be used to lower the overall risk of a portfolio.
The risk level for the remainder of the portfolio may be increased proportionally.

Annualized total return calculator
To compare bonds to growth investments, calculate the annualized total return.
(Yield to maturity is a special case of total return.)

Bond portfolio ATR calculator
Calculate the annualized total return for each bond in a portfolio, and for the total portfolio.

Housewife proves that dryers violate the second law of thermodynamics.

It has long been observed that about 10% of the time, drying clothes results in an extra sock.  Maria del Paso, of Chico, California, has discovered that dryers are capable of turning heat into socks, explaining the appearance of the novel footwear.


The Mink program, analogous to the Weasel program

A MathJax Editor
Includes a WYSIWYG TeX or MathML editor, and SVG and .png converters.  Updated 5/26/2022.

Draw an Arc with MathJax

Golden Spiral Forever A golden spiral closely approximated by cubic Bézier curves. Created by Russell Cottrell; animated version at russellcottrell.com/blog.

Sacred Geometry

scripted with scalable vector graphics and html canvas elements.

Golden Spiral Forever
As the golden spiral rotates and zooms in, it paradoxically appears to remain stationary.

Drawing the Golden Spiral
Spoiler alert:  r = Φ2θ/π ⋅ (rectX/xMin).  Or closely approximate it with cubic Bézier curves.

Spin the Platonic Solids
Rotate the tetrahedron, cube, octahedron, dodecahedron, or icosahedron around any axis, or set them spinning.

Scripting the Shao Yong Diagram
The diagram that inspired Leibniz, ordered like binary numbers.

Straightedge Star
Draw a pentagon or star using only a straightedge and compass, Ptolemy’s (extremely simple) method.
And find the golden ratio in the process!

New Jersey man says he can bench press 500 lbs any time he feels like it.

“I just don’t feel like it,” he told reporters.

periodic table

Periodic Table of the Elements
Includes the Element Game, challenging you to find all the elements on the table.

More Element Games

Molecular Weight Calculator
Finally, a calculator that includes dot notation!  CaCl2·2H2O
Also includes Hill sorting, brackets as well as parentheses,
and non-integers for molecules of crystallization or non-stoichiometric compounds.


Calculate Pi to a Huge Number of Digits, like this:

RC Clock Works

The Celtic Wheel Horologium — indicates the current positions of the sun, moon, and stars, as well as the date with respect to the solstices, equinoxes, and cross-quarter days.  Use it to find the current sidereal and solar times, and the dates and times of the solar holidays and moon phases.

An Old English Lunisolar Calendar — based on first quarter moons beginning with the one before Yule.  This evening will be .

Sunset Calculator — enter your latitude and longditude and get sunset times for the whole year.

Solar and Lunar Data — current moon phase and relative size, and the positions of the earth and moon in their orbits.

Solar Events Calculator — solstices, equinoxes, and cross-quarter days, all at your fingertips.

Moon Phase Calculator — what moon phase were you born under?

Moon Perigee and Apogee Calculator — find the next supermoon.

Calculations are based on the “higher accuracy” equations in Astronomical Algorithms, second edition, by Jean Meeus, and the full VSOP87 data set.  They are much more accurate than spreadsheet calculations.

Study reveals that doctors are neither shocked, furious, nor speechless over quack internet remedies.

“They just kind of roll their eyes,” says the study’s author.

RC Clock Works

My grandfather’s pocket watch, in SVG format that runs!

I bet you wish you were using Linux.

 July-August-September 2020
 Su Mo Tu We Th Fr Sa
           1  2  3  4 
  5  6  7  8  9 10 11 
 12 13 14 15 16 17 18 
 19 20 21 22 23 24 25 
 26 27 28 29 30 31  1 
  2  3  4  5  6  7  8 
  9 10 11 12 13 14 15 
 16 17 18 19 20 21 22 
 23 24 25 26 27 28 29 
 30 31  1  2  3  4  5 
  6  7  8  9 10 11 12 
 13 14 15 16 17 18 19 
 20 21 22 23 24 25 26 
 27 28 29 30 

A three-month Bash calendar


A color-managed Linux workflow

Excerpt:  if you have a color profile for your monitor, copy it to a folder with public access, such as ~/.local/share/color/icc.
Make sure you have ArgyllCMS installed, or at least the dispwin executable.
Then use this command to create a startup application entry that sets the profile automatically:
dispwin ~/.local/share/color/icc/monitor.icc

Using PhotoLine in Linux  (see Notes on Linux installation)


Taken 7/15/2020 just after 10:00 p.m. north of Chico, California.
ISO 800, 8 seconds at f/4, 145mm focal length.

How to see Comet NEOWISE at earthsky.org

San Gabriel Mission

Los Angeles Times, What the fire at San Gabriel Mission left behind.  The house I used to live in is in the little subdivision at the upper right.
See also ‘My heart is full of sadness’: Faithful stunned by destruction of San Gabriel Mission fire

camp fire

The Camp Fire, 11/8/2018, 8:17 a.m. looking over the ridge toward Paradise and Concow.  The fire had started at 6:29 a.m. seven miles north of town, and when this picture was taken, Paradise was already evacuating.

camp fire

8:40 p.m.; the fire topped the ridge about a mile away and started down the hill toward us.  Evacuated shortly thereafter.

Livable Planet

Livable Planet at the Chico Art Center.

Bay Area man learns that Abraham Lincoln was born on his birthday.

“February 12 was always my special day,” says Frank Anderson.  “But now they say Abraham Lincoln was born on that day too.  I guess it’s not so special after all.”

eclipse 2007

Watching an eclipse during the hour-plus between first contact and totality is like watching the minute hand of a clock; there is not much visible movement.  Until the very end when the crescent gets down to about the last 1/6 of the sun’s circumference; at that point it shrinks before your very eyes until it disappears as if being swallowed up.  With bated breath you take off your solar glasses, and hanging in the sky is an object of otherworldly grandeur.  You sort of knew what to expect, but could not have imagined this.  Amid a groundswell of oohs, aahs, and astonished whoas, you stare at it with your mouth open.

Everyone who has seen the corona says photographs do not do it justice.  When you see it for yourself you know what they mean.  It looks almost fluffy, three-dimensional, with a black disk stamped into it.  It has lots of fine detail and gradation as if made of mother-of-pearl.  This against the dark royal blue sky gives it a glowing jewel-like appearance.

Experienced eclipse chasers say not to photograph your first eclipse; just watch it and let it sink in.  After 15 or 20 seconds I couldn’t stand it and tried to get a few pictures.  Watching, fiddling with the camera, watching again; then, inexorably, the diamond ring reappears and it’s all over.  Time to put the glasses back on.  A number of people clap as if to praise a fine performance.  It was the shortest minute and fifty seconds of my life.  One more item checked off of the bucket list.

Spray, Oregon, 8/21/2017
First contact at 09:08
Totality at 10:21, duration 1:50

Composite of two photographs, foreground and sky, with color and brightness adjusted to match my recollection of the scene.


The planet Venus in a clear blue sky, 6/12/2013

guest blogger

Custom Art Framing:  Guest Blogger at frameusa.com.

The JavaScript Chessboard

The Chess960 Numbers Decoded
Convert to and from Chess960 numbers mathematically, without lookup tables.

transit of Venus

Transit of Venus, 6/5/2012

annular eclipse
Annular eclipse of 5/20/2012
Chico, California
annular eclipse
annular eclipse

Humboldt fire

The Humboldt fire, 6/13/2008.

Humboldt fire

A curmudgeon’s guide to grammar and usage

Short-lived rhymes with long-knived.
If you are short of hands, you are short-handed.  If you are short of wind, you are short-winded.  If you are short of life, you are short-lived.  Think about it . . . .

A page that says “This page intentionally left blank” is no longer blank.

Data is the plural of datum.  It’s something like facts.  “These data show . . . .”
Media is the plural of medium.  “Back up your files on another medium.”  “Insert a blank medium.”
Criteria is the plural of criterion.  “The first criterion . . . .”

Kudos (κῦδος) is the Greek word for “praise” and is singular.  There is no such thing as a kudo.

Less refers to a continuous quantity; fewer refers to a discrete number.  If you are on a diet, eat fewer cookies and drink less milk.

One thing is centered on another; nothing is centered around anything.  The center is a point.

Pitiful means full of pity, as joyful means full of joy.
Something that arouses pity is piteous, or pitiable.

Nauseous means causing nausea, something like hideous.
When you feel nausea, you are nauseated.

Mischievous has three syllables and is pronounced “MIS-che-vus.”  It comes from the word mischief.
“Mis-CHEE-vee-us” is not a word.

Coitus has three syllables and is pronounced “co-EE-tus.”  It literally means “going together.”
Compare it to coaxial, coexist, coincide, cooperate, coefficient, coenzyme . . . .
(One would think Sheldon Cooper would know this; but they say it wrong in practically every episode.)

Between you and me:
It is you; it is I.  It is you and I.
It is for you; it is for me.  It is for you and me.
It is with you and me.  It is between you and me.
Again:  It is between you and me.  Always and forever.

Things differ from each other.
“This differs from that.”  “This is different from that.”  Similar to, different from; it all makes sense.
Practice saying it:  “different from; different from; different from.”
(Side note:  if you are comparing things that differ from something else, you might say, “this is more different than that is.”)

None is short for “not one” and is singular.
“None is left,” not “none are left.”
“None of the members is left,” not “none of the members are left.”
Sure, you can use a plural verb.  You can also use “ain’t” in your resume and call your boss a geek.  It’s a free country.

In defense of the “Oxford comma”:
What do you indolent, stuporous people have against a fricking comma?  Leaving it out can completely change the meaning of a sentence.
“Last night I met two prostitutes, your mother and your sister.”
“Last night I met two prostitutes, your mother, and your sister.”

These ( ) are parentheses, these [ ] are brackets, and these { } are braces.
You don’t have to say “square brackets” or “curly braces,” and “curly brackets” just confuses the issue.

“I feel badly” means that when you try to identify something by touch, you do a poor job.
“I feel bad” means that you are experiencing distress.  It’s like “I look bad” or “I am bad.”

Apostrophes that look wrong but aren’t:  the plurals of non-words use apostrophes to prevent ambiguity.
“Mind your p’s and q’s.”  “The 1930’s were difficult years.”
Some people disagree with this.  I feel bad for them.

There is nothing wrong with using first person in formal writing.  Third-person circumlocutions like “this writer” get tiresome very fast and should die.
Similarly, using myself as a way to avoid saying I or me is usually just plain wrong.
I tell it like it is.

Please visit russellcottrell.com.