Results of DEM reconstructions from simulated SDO/AIA data of a single Gaussian model. Shown is the zeroth-order regularized solution (left panel, red error bars) and with an additional positivity constraint (middle panel, blue error bars). The resulting simulated SDO/AIA data for each filter and the residuals of the regularized solutions are shown in the upper and lower right panels. Also plotted is the solution from xrt_dem_iterative2.pro (grey histogram, left panel) and the EM loci curves (purple lines, left panel).