I just write this thread because there still have questions about dot and cross products here, and I remeber that I wrote some other threads about them (links at the end).
Some reminders about differences between cross product and dot product.
The first one is important, the cross product creates a vector, the dot product creates a number !
Graphically, the dot can be represented like this :
The same way for the cross :
The problem about the cross product with PC-DMIS, is that the result is always a unit vector (the result is divided by its own length).
So you can't use it directly to calculate angles or distances.
I just ran into the cross product returning the unit vector after beating my head against the wall for an hour trying to figure out why my point-to-line code wasn't working. Ugh... It would be helpful if that defect was at least stated in the documentation.
There's a very old thread (or maybe it was a phone answer) in which I asked the question, the answer was "there's a cross_only function inside the soft, but it's not accessible to users", or something like this.
In the thread above, "cross_only" function should be "P_Vect" ("produit vectoriel" in french )
mbatten : I'm sorry, I'm not sure to understand the first question... If you want an accurate result, you have to use the max decimal places.
If you calculate a lonfg vector with only 3 decimal places, I'm not sure that the result is good (I will check it, asap )
For the second, I remember now, it has been "reported" long time before I registered on the forum. As usual, the answer was : " it works as it's concepted"...
There's a somewhat messy formula to compute the cross product using the X, Y, and Z coordinates of each vector. I was just wondering if it would give a more accurate result in some situations.
!
If you want an accurate result, you have to use the max decimal places.
