Line Integral Calculator

∫C F·dr along curves

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About Line Integral Calculator

A line integral calculator for scalar and vector line integrals. Computes ∫C f ds (scalar) and ∫C F·dr (vector) along parametric curves. Select from preset curves and fields. Shows parameterization, evaluation, and result. All calculations are client-side.

Line Integral Calculator Features

  • ∫C F·dr
  • ∫C f ds
  • Parametric
  • Presets
  • Step-by-step
Line integral: ∫C F·dr = ∫ₐᵇ F(r(t))·r'(t)dt. Scalar: ∫C f ds = ∫ₐᵇ f(r(t))|r'(t)|dt. Work done by force along path. Conservative fields: ∫C ∇f·dr = f(B)−f(A) (path independent). Green's theorem converts to double integral.

How to Use

Select curve and field:

  • C: Parametric curve r(t)
  • F: Vector field
  • Output: ∫C F·dr

Conservative Fields

F = ∇f ⟺ ∫C F·dr path-independent ⟺ ∮ F·dr = 0. Test: ∂F₁/∂y = ∂F₂/∂x (2D). If conservative, find potential f and use f(B)−f(A).

Applications

  • Work: W = ∫C F·dr
  • Circulation: ∮C F·dr
  • Arc length: ∫C 1 ds
  • Mass of wire: ∫C ρ ds

Step-by-Step Instructions

  1. 1Select curve.
  2. 2Select field.
  3. 3Parameterize.
  4. 4Evaluate integral.
  5. 5Get result.

Line Integral Calculator — Frequently Asked Questions

What is the difference between ∫F·dr and ∫f ds?+

∫F·dr is a vector line integral (dot product with tangent direction) — gives work/circulation. ∫f ds is a scalar line integral (multiply by arc length element) — gives mass, charge, etc. Vector version depends on direction; scalar doesn't.

How do I check if a field is conservative?+

In 2D: ∂F₁/∂y = ∂F₂/∂x. In 3D: curl F = 0 (∇×F = 0). If the domain is simply connected and these hold, F is conservative. Then find potential f by integrating: ∂f/∂x = F₁, ∂f/∂y = F₂.

What is Green's theorem?+

∮C (P dx + Q dy) = ∬D (∂Q/∂x − ∂P/∂y) dA. Converts a line integral around a closed curve to a double integral over the enclosed region. Special case: area = ½∮(x dy − y dx).

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