# tri.find

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##### Locate a point in a triangulation

This subroutine locates a point $P=(x,y)$ relative to a triangulation created by tri.mesh. If $P$ is contained in a triangle, the three vertex indexes are returned. Otherwise, the indexes of the rightmost and leftmost visible boundary nodes are returned.

Keywords
spatial
##### Usage
tri.find(tri.obj,x,y)
##### Arguments
tri.obj

an triangulation object of class triSht

x

x-coordinate of the point

y

y-coordinate of the point

##### Value

A list with elements i1,i2,i3 containing nodal indexes, in counterclockwise order, of the vertices of a triangle containing $P=(x,y)$. bc contains the barycentric coordinates of $P$ w.r.t. the found triangle.

If $P$ is not contained in the convex hull of the nodes this indices are 0 (bc is meaningless then).

triSht, print.triSht, plot.triSht, summary.triSht, triangles, convex.hull

• tri.find
##### Examples
# NOT RUN {
data(franke)
tr<-tri.mesh(franke$ds3$x,franke$ds3$y)
plot(tr)
pnt<-list(x=0.3,y=0.4)
triangle.with.pnt<-tri.find(tr,pnt$x,pnt$y)
attach(triangle.with.pnt)
lines(franke$ds3$x[c(i1,i2,i3,i1)],franke$ds3$y[c(i1,i2,i3,i1)],col="red")
points(pnt$x,pnt$y)
# }

Documentation reproduced from package interp, version 1.0-33, License: GPL (>= 2)

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