traJ

Traj is an abbreviation of trajectory, a term used across science and engineering to denote the time-ordered path traced by a moving object or evolving system. In physics and classical mechanics, a trajectory describes the coordinates of a particle as a function of time and may include velocity and acceleration. In mathematics, trajectories arise from dynamical systems and flows, representing the orbit of a point under a map or differential equation.

In applied fields, traj commonly appears as a data structure, a variable name, or a software object that stores a sequence of poses or positions over time. In robotics and motion planning, a trajectory specifies the position, orientation, and possibly higher derivatives along a time parameter, with attention to constraints such as collision avoidance and actuator limits. In computer graphics and animation, trajectories define the motion of objects for rendering. In astronomy, a trajectory describes the path of a body under gravitational forces.

In computational chemistry and molecular dynamics, traj often refers to trajectory data produced by simulations. Trajectory files record atomic coordinates at discrete time steps and may use formats such as DCD, XTC, TRR, or XYZ. Software tools such as MDTraj, MDAnalysis, and PyTraj read and analyze these trajectories to compute distances, root-mean-square deviations, diffusion properties, and other metrics.

Notationally, traj is frequently used as a variable or function name representing a sequence of states over time. Trajectory analysis commonly involves smoothing, resampling, alignment, or parameterization by arc length, and trajectory optimization is a key topic in control theory and robotics.