A straight section built with one-dimensional truss elements is used in a dynamic analysis. The model has a displacement boundary condition prescribed at node 2, a velocity boundary condition prescribed at node 3, and an acceleration boundary condition prescribed at node 4 using user subroutine VDISP. For comparison purposes a displacement variation is specified at node 5, a velocity variation is specified at node 6, and an acceleration variation is specified at node 7 using amplitude functions. The variation prescribed is

for displacement and for velocity and acceleration. The cosine contribution is excluded in selecting the displacement amplitude function to avoid an initial jump in the displacement. For the variations specified using VDISP, the appropriate functions have to be incorporated into the subroutine. Identical variations are specified in both methods such that the results should be identical.