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Double pendulum · mimo-v2.5

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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transcript · 4 messages
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
The user wants a double pendulum simulation on a canvas with proper equations of motion, drawing arms and a fading trail of the tip. This is a physics simulation that requires:

1. The correct coupled differential equations for a double pendulum
2. Numerical integration (Runge-Kutta 4th order would be nice)
3. Canvas rendering with arms drawn and a colorful fading trail

Let me write this as a single self-contained HTML file.

The equations of motion for a double pendulum (from Lagrangian mechanics):

For the double pendulum with masses m1, m2, lengths l1, l2, angles θ1, θ2:


I'm setting up the coupled differential equations where the angular accelerations depend on both angles and velocities through complex trigonometric relationships. Now I'll implement this with RK4 integration and a colorful fading trail effect.
write /workspace/index.html (7039 bytes)
toolResult

Successfully wrote 7039 bytes to /workspace/index.html

assistant
thinking
The file has been written. Let me verify it's there.

Done — `index.html` is written and self-contained. Here's what it does: **Physics** - Solves the full coupled Lagrangian equations of motion for the double pendulum - Uses **4th-order Runge-Kutta** integration (4 sub-steps per frame) for numerical stability **Rendering** - Draws the two arms from pivot → mass 1 → mass 2 (tip) - Maintains an 800-point **color-cycling HSL trail** behind the tip that fades with age - Adds a radial glow at the tip; each mass gets a subtle gradient **Interactions** - **Click anywhere** to fling the pendulum toward/away from that point - **Reset** — back to a fixed starting position - **Randomize** — random angles and velocities for chaotic new orbits - **Trail On/Off** — toggle the trail

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

modelmimo-v2.5
vendorXiaomi · MiMo
harnesspi-agent
generated2026-07-08

EVALUATION

4/5 working

Double pendulum simulates chaotic motion with colorful fading trail forming symmetric mandala patterns over time.

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 motion1.7%
on click13.8%
on drag12.7%
on wheel15.9%
on enter + space15.7%
on arrow keys14.3%
on w/a/s/d12.2%
frame spread32 / 255
console errors0
js errors none

METRICS

runtime28.1s
tokens in3.5k
tokens out3.0k
cached2.7k
cost / run$0.0013