PPolySim OS

Numerical Integration

Quadrature made visible. Approximate the area under a curve with five classic rules and watch how fast each one converges to the true integral.

Numerical IntegrationLive

Controls

Function

Method

Each method approximates the shaded area under f(x). Add subintervals — or switch to Simpson — to watch the error collapse.

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Data Inspector

Estimate1.96662
Exact1.98999
|Error|2.338e-2
n8
MethodTrapezoid

Governing equation

Reading this result: Trapezoid has error O(h²), so halving the step cuts the error by ~4×. It only tracks the slope, not the curvature, so it trails Simpson badly on smooth functions. Here |error| = 2.34e-2 at n=8 (h=0.375). For smooth f, switching to Simpson typically buys several extra digits of accuracy at the same n.

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How it works

Numerical integration (quadrature) estimates a definite integral by sampling f(x) and summing simple shapes: flat-topped rectangles (Left, Right, and Midpoint Riemann sums), straight-line trapezoids, or parabolic arcs (Simpson's rule). The plot shades the exact regions each method uses. Compare the estimate against the analytic value to see the error orders in action — trapezoid converges as O(h²) while Simpson reaches O(h⁴), so Simpson buys several extra digits of accuracy for smooth functions at the same number of subintervals.

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Frequently asked questions

Is this numerical integration Simpson trapezoid tool really free?
Yes. Numerical Integration runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.