Quick Start
- Prepare a CSV file with two columns:
x and y.
- Upload it via the sidebar — drag & drop or click to browse.
- Adjust the polynomial degree slider to control the curve complexity.
- Read the fitted equation and R² in the Series table.
CSV Format — Single Series
Two columns per row, comma or semicolon delimited. A header row is optional and detected automatically.
x,y
-3,8.7
-2,3.9
-1,0.8
0,0.1
1,1.2
CSV Format — Multiple Series
Separate each series with a blank line. Optionally add a name on the line just above the data.
Measurement A
x,y
0,1.2
1,3.5
2,6.8
Measurement B
x,y
0,0.4
1,1.9
2,4.1
Up to 20 series can be loaded at once.
Polynomial Degree
The slider sets the degree d of the fitted polynomial:
- 1 — straight line (linear)
- 2 — parabola (quadratic)
- 3 — cubic curve
- d — requires at least d + 1 data points
Higher degrees fit the data more closely but may overfit noise. Start low and increase until R² stops improving significantly.
Understanding R²
R² (coefficient of determination) measures how well the curve fits the data:
- R² ≥ 0.99 — excellent fit
- R² ≥ 0.90 — good fit
- R² < 0.90 — poor fit — try a higher degree
Series Panel
Each row in the Series table represents one curve. Click any row to toggle its visibility on the chart. The eye icon on the right also acts as a toggle.
The in-chart legend shows up to 6 series; if more are visible it displays +N more…
Coefficients Table
The Coefficients section shows the exact polynomial coefficients for each series:
y = a₀ + a₁x + a₂x² + … + aₙxⁿ
Coefficients are displayed with 8 significant figures.