pcds (version 0.1.2)

isStdEqTri: Check whether a triangle is a standard equilateral triangle

Description

Checks whether the triangle, tri, is the standard equilateral triangle \(T_e=T((0,0),(1,0),(1/2,\sqrt{3}/2))\) or not.

Usage

isStdEqTri(tri)

Arguments

tri

Three 2D points, stacked row-wise, each row representing a vertex of the triangle.

Value

TRUE if tri is a standard equilateral triangle, else FALSE.

Examples

# NOT RUN {
A<-c(0,0); B<-c(1,0); C<-c(1/2,sqrt(3)/2);
Te<-rbind(A,B,C)  #try adding +10^(-16) to each vertex
isStdEqTri(Te)

isStdEqTri(Te)

Te<-rbind(B,C,A)
isStdEqTri(Te)

Tr<-rbind(A,B,-C)
isStdEqTri(Tr)

A<-c(1,1); B<-c(2,0); C<-c(1.5,2);
Tr<-rbind(A,B,C);
isStdEqTri(Tr)

A<-c(0,0); B<-c(1,0); C<-c(.5,0.8660254);
Te<-rbind(A,B,C)
isStdEqTri(Te)

isStdEqTri(rbind(A,A,B))

dat.fr<-data.frame(a=Te)
isStdEqTri(dat.fr)

# }