I'm a professor of mathematics at the University of North Carolina Asheville. I've also done a fair amount of consulting work over the years focusing on scientific and data visualization.
I'm happy to be part of the first Observable Ambassador's cohort.
Public
Edited
Feb 10, 2023
2 stars
// Generate an image of the nth legal kings row of length 8
function row_pic(n) {
let row_pic = Plot.plot({
width: 800,
height: 100,
margin: 0,
x: { domain: [0, 8] },
y: { domain: [0, 1] },
marks: [
Plot.rect(d3.range(1, 10, 2), {
x1: (d) => d,
x2: (d) => d + 1,
y1: 0,
y2: 1,
fill: "#ddd",
stroke: "#ddd"
}),
Plot.line(
[
[0, 0],
[8, 0],
[8, 1],
[0, 1],
[0, 0]
],
{ stroke: "#ccc" }
)
]
});
let matches = rows[n].matchAll(/K/g);
let match_result = matches.next();
while (!match_result.done) {
d3.select(row_pic)
.append("g")
.attr(
"transform",
`translate(${row_pic
.scale("x")
.apply(match_result.value.index)}) scale(2.2)`
)
.append(() => svg`${king}`);
match_result = matches.next();
}
return row_pic;
}
// Recursive construction of the set of all legal rows of length 8
rows = {
let extend1 = (s) => s + "1";
let extend2 = (s) => s + "1K";
let rows = [
["K", "1"],
["1K", "K1", "11"]
];
for (let i = 0; i < 6; i++) {
rows.push([rows[0].map(extend2), rows[1].map(extend1)].flat());
rows.shift();
}
return rows[1].reverse();
}
// https://commons.wikimedia.org/wiki/Category:SVG_chess_pieces
king = `<svg xmlns="http://www.w3.org/2000/svg" width="45" height="45">
<g fill="none" fill-rule="evenodd" stroke="#000" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.5">
<path stroke-linejoin="miter" d="M22.5 11.63V6M20 8h5"/>
<path fill="#fff" stroke-linecap="butt" stroke-linejoin="miter" d="M22.5 25s4.5-7.5 3-10.5c0 0-1-2.5-3-2.5s-3 2.5-3 2.5c-1.5 3 3 10.5 3 10.5"/>
<path fill="#fff" d="M12.5 37c5.5 3.5 14.5 3.5 20 0v-7s9-4.5 6-10.5c-4-6.5-13.5-3.5-16 4V27v-3.5c-2.5-7.5-12-10.5-16-4-3 6 6 10.5 6 10.5v7"/>
<path d="M12.5 30c5.5-3 14.5-3 20 0m-20 3.5c5.5-3 14.5-3 20 0m-20 3.5c5.5-3 14.5-3 20 0"/>
</g>
</svg>`
function fibonacci(n) {
let a = 0;
if (n == 0) {
return a;
}
let b = 1;
if (n == 1) {
return b;
}
if (n > 102) {
a = BigInt(a);
b = BigInt(b);
}
for (let i = 0; i < n - 1; i++) {
let F = a + b;
a = b;
b = F;
}
return b;
}
import { step_slider } from "59730aabd7354b99"
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