center: Center rotation data

In rotations: Working with Rotation Data

Center rotation data

Description

This function will take the sample Rs and return the sample Rs centered at S. That is, the ith observation of Rs denoted Ri is returned as S'Ri. If S is the true center then the projected mean should be close to the 3-by-3 identity matrix.

Usage

center(x, S)

## S3 method for class 'SO3'
center(x, S)

## S3 method for class 'Q4'
center(x, S)

Arguments

x	n-by-p matrix where each row corresponds to a random rotation in matrix (p=9) or quaternion (p=4) form.
S	the rotation or a matrix of n-by-p rotations about which to center each row of x.

Value

The sample centered about S

Examples

Rs <- ruars(5, rcayley)
cRs <- center(Rs, mean(Rs))
mean(cRs)                      #Close to identity matrix

all.equal(cRs, Rs - mean(Rs))  #TRUE, center and '-' have the same effect
                               #See ?"-.SO3" for more details

center(Rs,Rs)                  #n-Identity matrices: If the second argument is of the same dimension
                               #as Rs then each row is centered around the corresponding
                               #row in the first argument

rotations documentation built on June 25, 2022, 1:06 a.m.