Boundary conditions in 1D
The idea that a boundary condition applies along the length of a boundary segment, while meaningful in two and three dimensions, is meaningless in one dimension, since it is the value along the segment that is the object of the computation.
In one dimensional problems, therefore, it is necessary to use the Point boundary condition described in the previous section for all boundary condition specifications.
START(0) POINT VALUE(u)=1
LINE TO (5) POINT LOAD(u)=4
The node at coordinate 0 will have value 1, while that at coordinate 5 will have a load of 4.