vecproj: Vector Projection

In geophys: Geophysics, Continuum Mechanics, Gravity Modeling

Description

Vector Projection information, such as angle and distances between points

Usage

vecproj(P1, P2)

Arguments

P1	Point 1
P2	Point 2

Details

The distances returned are the legs of right right triangles where the cosine of the angle is used to get the projection distance of the opposite side on the specified direction. See the example for an illustration.

Value

cang=cang, angrad=angrad, angdeg=angdeg, dis1=d1, dis2=d2

cang	cosine of angle between points
angrad	angle, radians
angdeg	angle, degrees
dis1	distance
dis2	distance

Author(s)

Jonathan M. Lees<[e-mail]>

See Also

perpproj

Examples

P1 = c(2, 3)
P2 = c(5, 2)


I = vecproj(P1, P2)


plot(c(0, P1[1], P2[1]), c(0, P1[2], P2[2]), asp=1, ann=FALSE)

arrows(0, 0, P1[1],  P1[2], length=.1)
arrows(0, 0,  P2[1],  P2[2], length=.1)

text(P1[1],  P1[2], "Point 1", pos=3)
text(P2[1],  P2[2], "Point 2", pos=3)

j1 = atan2(P1[2], P1[1])*180/pi
j2 = atan2(P2[2], P2[1])*180/pi

L1 = vlength(P1)
L2 = vlength(P2)

A = GEOmap::darc(L1*.2, j1, j2, 0, 0, n=1)

lines(A)
an = length(A$x)
arrows(A$x[an-1] , A$y[an-1] ,A$x[an] , A$y[an] ,  length=.08 )

text(A$x[an/2] , A$y[an/2], labels=format(I$angdeg, digits=4)  , pos=4)


 V1 = c( 0,P1[1], 0,  P1[2])
   V2 = c( 0,P2[1], 0,  P2[2])
  

    PP = perpproj( V1, V2, add=FALSE  )

arrows(P1[1],P1[2],PP$P2[1], PP$P2[2],  length=.07, lty=2, col='red') 
arrows(P2[1],P2[2],PP$P1[1], PP$P1[2],  length=.07, lty=2, col='blue') 

 labelLine( c(0, 0) , PP$P2 , lab="dis1", dinch = .25, aty=1,
acol='blue', above=FALSE  )


 labelLine( c(0, 0) , PP$P1 , lab="dis2", dinch = .25, aty=1,
acol='blue'  )

geophys documentation built on May 1, 2019, 9:26 p.m.