Maths & numbers

Polynomial interpolation workspace

Interpolate up to 20 points and export a sampled polynomial curve.

Polynomial interpolation workspace
Esc to restore

Your inputs

Exact X,Y headings. Plain finite coordinates within ±1 billion.

Up to 25 MB per file, 50,000 data rows, 200 columns and 2 million data cells. Fully blank rows and columns are ignored before row, column and cell limits are checked. Individual tools may have smaller result or chart limits.

Results update as you type. Larger files run when you press Update result.

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Your result

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A clear answer. Here’s how.

Uses barycentric Lagrange interpolation after centring and scaling X to improve numerical behaviour. Supports 2–20 distinct, adequately separated X values; sorts points by X. First output row is the query, followed by 101 samples over the input range. High-degree interpolation and extrapolation can oscillate or be poorly conditioned; this does not perform regression or infer uncertainty.

See a worked example

Worked example

A fixed demonstration, separate from the values you enter above.

CSV: X,Y
X,Y
0,1
1,2
2,5
3,10
Query X
1.5

Example result

First 5 rows of the example result
XInterpolated Y
1.53.25
01
0.031.0009
0.061.0036
0.091.0081

First row is your query; remaining rows sample the supplied X range. Barycentric polynomial interpolation; high degree or clustered points can be unstable. Avoid extrapolation.

Keep going.

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