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Double pendulum · muse-glimmer-30b

Simulate a chaotic double pendulum on a canvas using the correct equations of motion, drawing the arms and a colorful fading trail of the tip.

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user

Simulate a chaotic double pendulum on a canvas using the correct equations of motion, drawing the arms and a colorful fading trail of the tip.

assistant
thinking
Simulate a chaotic double pendulum on a canvas using correct equations of motion, drawing arms and colorful fading trail of tip. Build single-page web app write it ALL into one self-contained file named index.html in current directory: CSS in <style>, JS in <script>, inline — do not create separate .css/.js files. Use NO external resources, CDNs or network requests.

We need write index.html. Use canvas. Double pendulum equations.

Standard equations:
Let l1,l2, m1,m2, g.
θ1, θ2 angles from vertical.
ω1, ω2 angular velocities.

Equations:
den1 = l1*(2*m1 + m2 - m2*cos(2θ1 - 2θ2))
num1 = -g*(2*m1+m2)*sinθ1 - m2*g*sin(θ1-2θ2) - 2*sin(θ1-θ2)*m2*(ω2^2*l2 + ω1^2*l1*cos(θ1-θ2))
α1 = num1 / den1

den2 = l2*(2*m1 + m2 - m2*cos(2θ1-2θ2))
num2 = 2*sin(θ1-θ2)*( ω1^2*l1*(m1+m2) + g*(m1+m2)*cosθ1 + ω2^2*l2*m2*cos(θ1-θ2) )
α2 = num2 / den2

That's standard.

Alternatively use Lagrangian.

We'll implement simulation with RK4 or simple Euler with small dt. Better use semi-implicit Euler or RK4 for stability.

We'll draw arms and trail with fading. Colorful fading trail: we can store points array, draw with gradient opacity.

Make controls? Might be nice to have reset button and sliders for masses/lengths? Could keep simple.

Requirement: single file. No external resources.

Implement canvas full window. Use requestAnimationFrame.

Draw arms: lines from origin (center top) to bob1 to bob2.

Trail: keep array of last N points (~500). Draw lines with color cycling hue based on time or position.

Colorful fading: use HSL hue = (time*... ) % 360.

Make background dark.

Implement with correct equations.

Let's create index.html.

We need ensure no external resources. Use pure JS.

Potential improvements: use devicePixelRatio.

We'll write file.

Let's check current directory.
bash {"command":"pwd && ls -la"}
toolResult

/tmp/ws total 0 drwxr-sr-x. 2 node node 6 Aug 13 01:25 . drwxrwsrwx. 3 root node 16 Aug 13 01:25 ..

assistant
thinking
Write index.html.
write /tmp/ws/index.html (6152 bytes)
toolResult

Successfully wrote 6152 bytes to /tmp/ws/index.html

assistant
thinking
We wrote file. Should confirm exists.
bash {"command":"ls -l /tmp/ws/index.html && head -c 200 /tmp/ws/index.html"}
toolResult

-rw-r--r--. 1 node node 6154 Aug 13 01:25 /tmp/ws/index.html <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Chaotic Double Pendulum</title> <meta name="viewport" content="width=device-width,initial-scale=1"> <style> html,body{margin:0;hei

assistant
thinking
Done. Provide summary.

Created a self-contained double pendulum simulation at **/tmp/ws/index.html**. It uses the correct Lagrangian equations of motion with RK4 integration, draws the two arms from a fixed pivot, and renders a colorful fading trail for the second bob. The UI lets you adjust lengths/masses, reset, toggle trail, and click-drag to give impulses — all in one HTML file with inline CSS/JS and no external resources. Open `index.html` in a browser to see the chaotic motion.

TAKE IT TO CODE

A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.

RUN

modelmuse-glimmer-30b
vendorMeta
harnesspi-agent
generated2026-08-13

EVALUATION

4/5 working

Double pendulum simulates chaotic motion with colorful fading tip trail, though clicking seems to reset/freeze it oddly.

Vision grade · anthropic/claude-sonnet-5

MEASUREMENTS

Raw readings from the capture, not a verdict — the grade above is the only judgement. Percentages are how much of the screen changed; the measure under-reports sparse motion on a dark background.

idle motion5.5%
on click3.0%
on drag0.0%
on wheel1.3%
on enter + space1.0%
on arrow keys0.0%
on w/a/s/d0.0%
frame spread20.8 / 255
console errors0
js errors none

METRICS

runtime35.1s
tokens in14k
tokens out3.0k
cached10k
cost / run$0.0059