Compute a small-circle path for a stereonet (degrees)

Computes the path(s) of a small circle defined by its rotation axis and cone angle on an equal-area or equal-angle stereonet of unit radius.

Usage

SmallCircleD(trda, plga, coneAngle, wulff = F, closed = F)

Arguments

trda

Numeric. Trend of the rotation axis in degrees.

plga

Numeric. Plunge of the rotation axis in degrees.

coneAngle

Numeric. Half-apex (cone) angle in degrees.

wulff

Logical. If TRUE uses an equal-angle (Wulff) net; if FALSE (default) uses an equal-area (Schmidt) net.

closed

Logical. If TRUE the path segments are closed by appending the first point to the end. Default FALSE.

Value

A named list with components:

path1

Tibble of stereonet coordinates for the main segment.

path2

Tibble of stereonet coordinates for the secondary segment.

References

Allmendinger, R. W., Cardozo, N., & Fisher, D. M. (2012). Structural geology algorithms: Vectors and tensors. Cambridge university press.

See also

Other structural algorithms: Angles(), CartToSphD(), GreatCircleD(), Pole(), Rotate(), SphToCartD(), StCoordLineD(), StPointD()

Examples

SmallCircleD(trda = 45, plga = 30, coneAngle = 20)
#> $path1
#> # A tibble: 360 × 2
#>       xp    yp
#>    <dbl> <dbl>
#>  1 0.643 0.643
#>  2 0.647 0.639
#>  3 0.650 0.635
#>  4 0.654 0.631
#>  5 0.658 0.627
#>  6 0.662 0.623
#>  7 0.665 0.618
#>  8 0.669 0.614
#>  9 0.672 0.610
#> 10 0.675 0.606
#> # ℹ 350 more rows
#> 
#> $path2
#> # A tibble: 0 × 0
#>