Lagranji

Lagranji is a numerical analysis tool that helps you visualize Lagrange interpolation polynomials in real time.

Tap anywhere on the canvas to place data points (up to 8). The app instantly computes the Lagrange interpolating polynomial and draws the smooth curve passing through all your points. View the expanded polynomial with all coefficients displayed.

Features:
Interactive canvas: tap to add data points, watch the curve update in real time
Polynomial display: see the full expanded polynomial with coefficients
Built-in examples: three equidistant points, four-point wave pattern, and two-point linear case
Random point generation for quick experimentation
Overfitting demonstration: toggle between 3, 5, and 8 points to observe Runge's phenomenon and understand why high-degree polynomials oscillate
Polynomial evaluation: enter any x value to compute P(x)
No account required. No data collected. Works entirely on your device.