spherepc (version 0.1.2)

Logmap: Logarithm map

Description

This function performs the logarithm map at (0, 0, 1) on the unit sphere.

Usage

Logmap(vec)

Arguments

vec

an element of the unit sphere in three-dimensional Euclidean space.

Value

two-dimensional vector.

Details

This function performs the logarithm map at (0, 0, 1) on the unit sphere. Note that, vec is normalized to be contained in the unit sphere.

References

Fletcher, P. T., Lu, C., Pizer, S. M. and Joshi, S. (2004). Principal geodesic analysis for the study of nonlinear statistics of shape. IEEE Transactions on Medical Imaging, 23, 995-1005.

See Also

Expmap.

Examples

# NOT RUN {
Logmap(c(1/sqrt(2), 1/sqrt(2), 0))
# }