Vector Projection Calculator

Project A onto B

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About Vector Projection Calculator

A vector projection calculator that computes the projection of vector A onto vector B. Shows scalar projection (comp_B A), vector projection (proj_B A), and the rejection (A − proj_B A). Supports 2D and 3D vectors. All calculations are client-side. Essential for physics, engineering, and linear algebra.

Vector Projection Calculator Features

  • 2D/3D
  • Scalar proj
  • Vector proj
  • Rejection
  • Angle
Vector projection of A onto B: proj_B(A) = (A·B/|B|²)B. Scalar projection: comp_B(A) = A·B/|B|. Rejection: A − proj_B(A) is perpendicular to B. The projection decomposes A into components parallel and perpendicular to B.

How to Use

Enter two vectors:

  • A: Vector to project
  • B: Direction to project onto
  • Output: Projection and rejection

Formulas

  • Scalar: A·B / |B|
  • Vector: (A·B / |B|²) × B
  • Rejection: A − proj_B(A)

Applications

Work in physics (F·d), shadow casting, decomposing forces, least-squares approximation, and signal processing.

Step-by-Step Instructions

  1. 1Enter vector A.
  2. 2Enter vector B.
  3. 3View scalar projection.
  4. 4View vector projection.
  5. 5Check rejection vector.

Vector Projection Calculator — Frequently Asked Questions

What's the difference between scalar and vector projection?+

Scalar projection is a number (the signed length of the shadow of A on B). Vector projection is a vector (the actual shadow vector, parallel to B).

What is the rejection vector?+

The rejection is A minus its projection onto B. It's the component of A perpendicular to B. Together, projection + rejection = A.

When is the projection zero?+

When A is perpendicular to B (A·B = 0). The entire vector A is 'rejected' — it has no component along B.

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