sl.angle | R Documentation |
Compute the angle between two edges of a triangle on a sphere.
sl.angle(lon, lat, return.degree = FALSE, left = FALSE)
lon |
a vector of length 3 specifying the longitudes of the triangle vertices; the angle is computed at the second vertex. |
lat |
a vector of length 3 specifying the longitudes of the triangle vertices; the angle is computed at the second vertex. |
return.degrees |
a logical value specifying whether the result shall be provided in degrees instead of radians (default). |
left |
a logical value specifying whether the angle to the left shall be returned. If |
The angle is computed at the second vertex. If left=FALSE
(default), the smaller of the two (left/right) angles is returned (angle<=pi
or angle<=180
). To get the right-side angle, set left=TRUE
and compute 2*pi-angle
(or 360-angle
).
A scalar giving the angle (on a unit sphere) in radians (default) or in degrees (if return.degree=TRUE
).
Helge Goessling
sl.angle(c(0,60,30),c(0,0,30))
## Should return:
## [1] 0.8570719
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