What are the forces on the particle from function O.forces.f()

I also want to know how to get the magnitude of each contact force of a particle.
Thank you

Hello,

please read [1] and provide a MWE

> Another question

please read [1] and create separate questions for separate problems.

> How does Yade add and subtract vectors and calculate the magnitude of a vector.

please read [1] and provide more information. How is it implemented? What is the equation? How to use it in Python? How to use it in C++? ... ?

> I also want to know how to get the magnitude of each contact force of a particle.

Iterate over particle's interactions and compute the magnitude from the interaction forces.
Could be something like:
###
particle = O.bodies[123]
for interaction in particle.intrs():
   force = interactipn.phys.normalForce + interaction.phys.shearForce
   magnitude = force.norm()
###

Cheers
Jan

[1] https://www.yade-dem.org/wiki/Howtoask

Thank you for your response. The problem is that I apply a force on a body via function O.forces.setPermF(), and then I use function O.forces.f() to get the resultant force on the body. Whether the resultant force includes the applied force and the contact force. In the documentation, the function O.forces.f() is described as:
Resultant force on body, excluding gravity.

In such a simple case, you can test it yourself:
###
b = sphere((0,0,0),1)
O.bodies.append(b)
O.forces.setPermF(0,(1,2,3))
O.step()
print(O.forces.f(0)) # Vector3(1,2,3)
###

So yes, "the resultant force includes the applied force and the contact forces"

Cheers
Jan

Thank you for your answer, which also brings me some ideas to solve the problem