Same problems here...

Hi d.tonelli

In this case you don't need the halfedge. As far as I understand, you want to use the index "i" to get the mesh face with the same index.
I commented out the line where you find the halfedge and used "i" directly to find the desired face.
_____________________________________
face = et.EmFace (strmesh, i)
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I also switched those two lines...
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Call et.EmDeleteFace (face)
arrPoints = et.EmGetFacePoints(face)
>>>>
arrPoints = et.EmGetFacePoints(face)
Call et.EmDeleteFace (face)
_____________________________________
...so that we get our face points before we delete the actual face.
I hope that your problems are solved now.
If you have any more questions, please don't hesitate to post them.
Regards,
Marko
_____________________________________
Option Explicit
'Script written by Marko Tomicic
'Script copyrighted by Evolute GmbH
'Script version Tuesday, December 18, 2012 21:54:10

Call Triangle_face_vertices_Coordinates()
Sub Triangle_face_vertices_Coordinates()
Dim et, strmesh, i, hedge, face, arrPoints
Set et = Rhino.GetPlugInObject( "EvoluteTools for Rhino" )
strmesh = Rhino.GetObject( "Select a Triangular Mesh ", 32 )
If IsNull(strmesh) Then Exit Sub
i = 20

'hedge = et.EmHalfedge (strmesh, i) 'unique halfedge handle

' Take the face directly
face = et.EmFace (strmesh, i) 'unique face handle - la face dialoga solo con l'halfedge

' Find points, then delete face
arrPoints = et.EmGetFacePoints(face)
Call et.EmDeleteFace (face)

Call Rhino.Print ("Point_0-(x,y,z): (" &arrPoints(0)(0) &" . "&arrPoints(0)(1)&" . "&arrPoints(0)(2)&")")
Call Rhino.Print ("Point_1-(x,y,z): (" &arrPoints(1)(0) &" . "&arrPoints(1)(1)&" . "&arrPoints(1)(2)&")")
Call Rhino.Print ("Point_2-(x,y,z): (" &arrPoints(2)(0) &" . "&arrPoints(2)(1)&" . "&arrPoints(2)(2)&")")
End Sub

Hi d.tonelli,
This script started assuming that a=1. It then set a=0 every time it found a boundary edge in the current face:
_______________________________________
If et.EmIsBoundary( hes( j ) ) Then
a = 0
Exit For
_______________________________________
It then proceeded only if a=1 which meant that the current face has no boundary edges:
__________________________________________________________
If a = 1 Then
___________________________________________________________

So basically by adding one to b (b=b+1) the script counted all faces which had no boundary edges.
I made a few minor changes, so the script should work fine now.

It now starts with a=0.
When looping through a face's edges we add: a=a+1 every time when we hit on a boundary edge.
Now, if there is one boundary edge "a" will be one, if the face has two boundary edges then a=2. If there are no boundary edges "a" stays zero.

In the next step we check if a=1. If it is, we add one to "b". This way the value which is stored in b increases by one every time we find a face with only one boundary edge. In the end we just have to print out the value which is stored in "b".
I hope this helps,
Marko
_________________________________________________________________

Option Explicit
'Script written by Marko Tomicic
'Script copyrighted by Evolute GmbH
'Script version Tuesday, December 18, 2012 21:45:45

Call Number_of_Double_Boundary_Faces()
Sub Number_of_Double_Boundary_Faces()
Dim et, strmesh, nfaces, hes, arrFacceInterne(), i, j, a, b
Set et = Rhino.GetPlugInObject( "EvoluteTools for Rhino" )
strmesh = Rhino.GetObject( "Select a Triangular Mesh", 32 )
If IsNull(strmesh) Then Exit Sub
nfaces = et.EmNumberOfFaces( strmesh )
b = 0
' Loop through all faces
ReDim arrFacceInterne(-1)
For i = 0 To nfaces-1
a = 0
hes = et.EmGetFaceEdges( strmesh, i )
' Loop through face edges
For j = 0 To 2
If et.EmIsBoundary( hes( j ) ) Then
a = a+1
End If
Next
If a = 1 Then
' Don't need the following two lines unless you want to collect the faces' indices into an array
ReDim Preserve arrFacceInterne(Ubound(arrFacceInterne)+1)
arrFacceInterne(Ubound(arrFacceInterne)) = i
' Add 1 to the number of boundary faces whit one boundary edge
b = b+1
End If
Next
Call Rhino.Print("Number of (triangular) faces which doesn't hold 2 boundary edges: " & CStr (b))
End Sub

Hi d.tonelli,
It should work when you replace
Call et.EmDeleteFace( strmesh, i )
with
Call et.EmDeleteFace( strmesh, 0 )

The problem was that in each new loop the script deletes one mesh face, so the total number of faces changes.
If you start with a mesh which consists of 20 faces, after three loops the mesh will have only 17 faces left, and so on.
After the loop repeats ten times and deletes half of the mesh faces, the mesh consists of only 10 faces (0-9). The script continues deleting faces with indices 10 to 19 which do not exist anymore.
By replacing "i" with "0" (zero) you will always delete the face which is currently at the first position (0) and you can be sure to get them all.
Regards, Marko

Hi, when using fairness optimization (FairnessSprings, FairnessCurvature, FairnessCurvatureVariation), it is important to do the following:

1) set a reference surface, and/or
2) set reference curves, and/or
3) fix some vertices.

Otherwise fairness optimization will collapse the mesh to a single point, i.e. the mesh does not disappear, but concentrates on a single point.
Please let me know if this solves your problem.
Regards, Alex