# MomentDist: Distance Between Moment Tensors In RFOC: Graphics for Spherical Distributions and Earthquake Focal Mechanisms

## Description

Calculate the distance between moment tensors based on quaternions.

## Usage

 `1` ```MomentDist(E1, E2) ```

## Arguments

 `E1` Moment tensor `E2` Moment tensor

## Details

Moment tensors should be right handed.

angle in degrees

## Author(s)

Jonathan M. Lees<[email protected]>

## References

Tape and Tape, 2012

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32``` ```Mtens = c(-0.412, 0.084, 0.328 ,0.398, -1.239, 1.058) M1 = matrix(c(Mtens[1], Mtens[4], Mtens[5], Mtens[4], Mtens[2], Mtens[6], Mtens[5],Mtens[6], Mtens[3]), ncol=3, nrow=3, byrow=TRUE) Mtens = c(5.054, -2.235, -2.819, -0.476, 5.420, 5.594) M2 = matrix(c(Mtens[1], Mtens[4], Mtens[5], Mtens[4], Mtens[2], Mtens[6], Mtens[5],Mtens[6], Mtens[3]), ncol=3, nrow=3, byrow=TRUE) E1 = eigen(M1) ### make sure these are a right handed system, ### ie x1 cross x2 = x3 E2 = eigen(M2) ### make sure these are a right handed system, ### ie x1 cross x2 = x3 testrightHAND(E1\$vectors) testrightHAND(E2\$vectors) E1\$vectors = forcerighthand(E1\$vectors) E2\$vectors = forcerighthand(E2\$vectors) testrightHAND(E1\$vectors) testrightHAND(E2\$vectors) MomentDist(E1, E2) ```