A novel approach to the calculation of powder lineshapes is as sums of lineshapes from symmetric tensors; these linepresented. Lineshapes from asymmetric second-rank tensor intershapes will be referred to as subspectra. This approach exactions are produced by summing lineshapes from symmetric tenploits the computer's ability to evaluate algebraic expressors. This approach significantly reduces the calculation time, sions quickly. The technique is called simulation using mulgreatly facilitating iterative nonlinear least-squares fitting of extiple subspectra, or SUMS. Because many simulations can perimental spectra. Results are reported for anisotropic 13 C NMR be performed in a short time, automated nonlinear leastlineshapes of glycine, benzoic acid, and octanoic acid in a urea squares fitting of experimental lineshapes is feasible, yieldinclusion compound. Lineshapes from nonuniform distributions ing results that do not rely upon subjective judgment of of crystallite orientations can also be calculated by using distributhe quality of fit. In addition, a modification of the SUMS tions of the Euler angles that define the orientation of the princialgorithm can be used to calculate lineshapes of partially pal-axis system of the chemical-shielding tensor with respect to the magnetic field.