vector_cross_product {stokes}

The Vector cross product

Description

The vector cross product \mathbf{u}\times\mathbf{v} for \mathbf{u},\mathbf{u}\in\mathbb{R}^3 is defined in elementary school as

\mathbf{u}\times\mathbf{v}=\left(u_2v_3-u_3v_2,u_2v_3-u_3v_2,u_2v_3-u_3v_2\right).

Function vcp3() is a convenience wrapper for this. However, the vector cross product may easily be generalized to a product of n-1-tuples of vectors in \mathbb{R}^n, given by package function vector_cross_product().

Vignette vector_cross_product, supplied with the package, gives an extensive discussion of vector cross products, including formal definitions and verification of identities.

Usage

vector_cross_product(M)
vcp3(u,v)

Arguments

M

Matrix with one more row than column; columns are interpreted as vectors

u, v

Vectors of length 3, representing vectors in \mathbb{R}^3

Details

A joint function profile for vector_cross_product() and vcp3() is given with the package at vignette("vector_cross_product").

Value

Returns a vector

Author(s)

Robin K. S. Hankin

See Also

cross

Examples

vector_cross_product(matrix(1:6,3,2))


M <- matrix(rnorm(30),6,5)
LHS <- hodge(as.1form(M[,1])^as.1form(M[,2])^as.1form(M[,3])^as.1form(M[,4])^as.1form(M[,5]))
RHS <- as.1form(vector_cross_product(M))
LHS-RHS  # zero to numerical precision

# Alternatively:
hodge(Reduce(`^`,sapply(seq_len(5),function(i){as.1form(M[,i])},simplify=FALSE)))