Ce n'est pas une coquille

3D Model

Generated by an R script using the rgl package.
Here is a code snippet:
h = 5
n = 3
u <- seq(0, 2pi, length.out=50);
v <- seq(0, 2pi, length.out=50);
wf <- function(u) { u/(2pi) }
xm <- outer(u,v,function(u,v)
wf(u)cos(nu)(1 + cos(v)))
ym <- outer(u,v,function(u,v)
wf(u)sin(nu)(1 + cos(v)))
zm <- outer(u,v,function(u,v)
wf(u)sin(v) + h * wf(u)^2)