Topic: ANGLE FORMED BY 2 PLANES so fast and infallible?

[Lee Mac]

Lee, don't have time to play ..
Does that return the  Dihedral angle ?

Correct, the angle between the normals 

No, The dihedral angle is between faces, not between normals.

The angle between the faces and the angle between the normals would be the same (up to sign) since the normals are perpendicular.

http://mathworld.wolfram.com/DihedralAngle.html

[SOFITO_SOFT]

Hello:
Kerry: You're an expert in magic numbers? Very goog test !. ACOS is not ready for magic numbers, else only for funky .Thanks.

[Kerry]

SOFITO_SOFT  

Sorry, English is my only language and I don't understand your meaning in the last post..

Just a note on the result you are expecting.

I asked how the data was being collected and you chose not to answer, so ...
I believe that the angle you are returning is useless without having a point of reference ... how do you know if the joint is viewed from the inside or the outside, whether the result is actually truly 15 degrees acute or 105 degrees convex or 165 degrees concave.

That is, I believe you need to provide a reference point to indicate which side of the planes the angle is measures.
In fact, planes are considered boundless, so you may also need to express (or consider) if you are assuming that the planes terminate at their intersection joint.

If the plane selection process is manual and the user has a chance to use his judgement the chance of misinterpretation is minimised somewhat ;
but if you are feeding your program large quantities of plane definition points and basing future decisions on possibly incorrect results I can see a lot of pain in your future.

Regards
Kerry

Picture added :

[SOFITO_SOFT]

Hello :
Sorry for my Paleolithic English . I only speak Spanish, French, Italian and some Basque. But Yes I've tried to answer:
 

I think that now is almost indestructible.

>>> The points are passed for other functions, such as "inters line / plan", "inters cone / line " "inters plan / planXY ", etc. <<<<

It has given me many problems here. ....

I explain: ACOS function not solve all cases. When the normal plans are equal and opposite, returns NIL. That's why I said that is only prepared for the "funky" (the easy) and not for "magical combiationes of coordinates", such as those you sent me for testing.

if you are feeding your program large quantities of plane definition points and basing future decisions on possibly incorrect results I can see a lot of pain in your future

  <<<<<  and I have. 

In fact, planes are considered boundless, so you may also need to express (or consider) if you are assuming that the planes terminate at their intersection joint.

<<<<< is a good idea four new implementations, but with those 2 angles I have solved (for now  ) my case.

Thanks and sorry for the misunderstanding. You are very attentive and patient with me.
Greetings from Madrid (Spain-UE).