Skip to contents

Mean strain ellipse

Source: R/strain_analysis.R
mean_strain_ellipse.Rd

determines the shape and orientation of the strain ellipse by using deformed elliptical objects as strain markers. The algorithm is based on the mean shape matrix and its eigenvalues (Shimamoto and Ikeda, 1976).

Usage

mean_strain_ellipse(r, phi, boot = TRUE, resamples = 1000, boot.values = FALSE)

Arguments

r

numeric. Aspect ratio of deformed object (long axis / short axis)

phi

numeric. Orientation of long axis of deformed object (in degrees)

boot

logical. Whether a 95% confidence interval from on bootstrapping should be calculated. TRUE by default.

resamples

integer. Number of bootstrap resamples (1000 by default). Ignored when boot = FALSE.

boot.values

logical. Whether the bootstrapped R and phi values should be added to the output. FALSE by default.

Value

list. R gives the mean aspect ratio of the strain ellipse, and phi gives the orientation of its long axis. If boot=TRUE, then the bootstrapped 95% confidence interval for the mean aspect ratio (R_CI) and for its orientation (phi_CI) are added. If boot.values=TRUE, a matrix containing the bootstrapped R and phi values are added.

References

Shimamoto, T., Ikeda, Y., 1976. A simple algebraic method for strain estimation from ellipsoidal objects. Tectonophysics 36, 315–337. doi: 10.1016/0040-1951(76)90107-4

See also

mean_strain_ellipse_ramsay()

Examples

set.seed(20250411)
data(ramsay)
mean_strain_ellipse(ramsay[, "R"], ramsay[, "phi"])
#> $R
#> [1] 1.628138
#> 
#> $phi
#> [1] 25.73632
#> 
#> $R_CI
#> [1] 1.59275 1.66359
#> 
#> $phi_CI
#> [1] 24.71905 26.75180
#>