Nonparaxial modeling of optical field propagation at distances comparable to the wavelength and under arbitrary spatial coherence is crucial for micro- and nano-optics. Fourier and Fresnel transform-based algorithms are unable to simulate it accurately because of their paraxial approach. A nonparaxial matrix algorithm, supported by the theoretical model that characterizes the optical field and the setup configuration in terms of sets of real and virtual point emitters, is capable of simulating the 3D optical field distribution in the volume delimited by the input and the output planes placed at a very short distance from each other by using experimental data as entries. The algorithm outcomes are accurate predictions of the power spectrum of interference and diffraction experiments. Simulations of specific experimental situations, including speckle phenomena, illustrate the algorithm's capabilities.