SageMath is a free open-source mathematics software system. You can use a SageMath cell online by going here.
The syntax described in section 2.1 generalizes to vectors in 3-space. Simply append a third component to your vectors.
v=vector([2,3,1])
--- Define the vector .v.norm()
--- Magnitude of .v.normalized()
--- Unit vector with the direction of . Same as .v=vector([2,3,1]); u=vector([-5,4,-2]); 3*v-2*u
--- Compute the vector .plot(v,color="red")
--- Plot the vector in red.a=plot(v,color="red"); b=plot(u,color="blue"); show(a+b)
--- Plot and .