This paper extends prior work on sparse tensor algebra compilers to generate asymptotically efficient code for tensor expressions with affine subscript expressions. Our technique enables compiler support for a wide range of sparse computations, including sparse convolutions and pooling that are widely used in ML and graphics applications. We propose an approach that gradually rewrites compound subscript expressions to simple subscript expressions with loops that exploit the sparsity pattern of the input sparse tensors. As a result, the time complexity of the generated kernels is bounded by the number of stored elements and not by the shape of the tensors. Our approach seamlessly integrates into existing frameworks and is compatible with recent advances in compilers for sparse computations, including the flexibility to efficiently handle arbitrary combinations of different sparse tensor formats. The implementation of our algorithm is open source and upstreamed to the MLIR sparse compiler. Experimental results show that our method achieves 19.5x speedup when compared with the state-of-the-art compiler-based method at 99.9% sparsity. The generated sparse kernels start to outperform dense convolution implementations at about 80% sparsity

Accurate knowledge of the at-surface solar irradiance (SSI) is essential to retrieving surface and atmospheric properties using satellite measurements of back-scattered and reflected radiance. The latter is affected by surface-atmosphere interactions, including the effects of terrain. The SSI is affected by the same processes. This study proposes a method to estimate the components of instantaneous surface solar irradiance: direct, isotropic and circumsolar diffuse, and terrain irradiance, which is expected to improve the simultaneous retrieval of Aerosol Optical Depth (AOD) and surface reflectance. The method takes into account the coupled effects of topography and atmosphere by combining parametrization and the Look-Up Table (LUT) approaches. The method was applied to rugged terrain over the Tibetan Plateau using MODIS atmosphere and surface data, ERA5 reanalysis data, CALIOP aerosol data and a Digital Elevation Model (DEM). The results showed that the SSI estimates were in satisfactory agreement with ground observations at four stations over the Tibetan Plateau in 2018 with R2values of 0.61, 0.44, 0.41, and 0.49, respectively, and RMSE of 205.7 W/m2, 176.9 W/m2, 186.0 W/m2, and 201.2 W/m2, respectively. Estimations of the diffuse irradiance were evaluated separately against the only available in-situ observations at the Dali Station and the results were better than our SSI estimates with R2, RMSE, and relative BIAS being 0.71, 94.98 W/m2, and 31%, respectively. The isotropic and circumsolar diffuse irradiance accounted for 37.57% and 7.68% of the total annual SSI respectively, while diffuse irradiance accounted for 46.48% of the total annual SSI. Under clear skies, every 0.1 increase in AOD caused about a 35 W/m2increase in diffuse irradiance and a decrease of about 25 W/m2of SSI.

Effect systems have been a subject of active research for nearly four decades, with the most notable practical example being checked exceptions in programming languages such as Java. While many exception systems support abstraction, aggregation, and hierarchy (e.g., via class declaration and subclassing mechanisms), it is rare to see such expressive power in more generic effect systems. We designed an effect system around the idea of protecting system resources and incorporated our effect system into the Wyvern programming language. Similar to type members, a Wyvern object can have effect members that can abstract lower-level effects, allow for aggregation, and have both lower and upper bounds, providing for a granular effect hierarchy. We argue that Wyvern’s effects capture the right balance of expressiveness and power from the programming language design perspective. We present a full formalization of our effect-system design, showing that it allows reasoning about authority and attenuation. Our approach is evaluated through a security-related case study.