Lagrange interpolation calculator

Calculate interpolated values in query order and global polynomial degree with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use interpolated values in query order and global polynomial degree to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Samples: x,y, one pair per line
0,1 1,2 2,5
Query x values
0.5,1.5
Interpolated values in query order
1.25, 3.25
Global polynomial degree
2
Queries outside sampled x range
0

Try another scenario

Samples: x,y, one pair per line
0,1 1,2 2,5
Query x values
0,1,2
Interpolated values in query order
1, 2, 5
Global polynomial degree
2
Queries outside sampled x range
0
Calculation method

Calculation method

Interpolated values in query order

Evaluate the barycentric Lagrange formula using weights 1/product(x_i−x_j); exact node queries return the original ordinate.

Global polynomial degree

Number of distinct samples minus one.

Queries outside sampled x range

Count query coordinates below the smallest or above the largest sample x.

Symbols and units
a
Samples: x,y, one pair per line
b
Query x values

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • One global interpolating polynomial through 2–25 distinct real nodes. High-degree interpolation and extrapolation can be ill-conditioned; no claim of an underlying physical model is made. Double-precision results are approximate. Numeric tables use 12 significant digits and display components at roundoff scale (32 machine epsilons relative to their row or relevant calculation scale) as zero; scalar diagnostics retain full precision.
Are these inputs private?

These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.

Further reading

SciPy: Lagrange interpolation ↗

Background reading; this does not imply endorsement or independent review of SumFizz.

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