Hi Amanda, I don't know what the SPI is, but most likely you want to calculate the TWI. This thread mixes up a lot of different topics. I order to help, we need more information about the error, the tools you use, and the dataset and how it is processed. Please refer to this page which lists some aspects that are required to provide an answer to questions. Best regards, Volker
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Variogram Surface, Principal Component Analysis (tables), Function Fit, Fill Minima: just fix some compiler warnings regarding data type conversion (possible loss of data)
Count Points in Polygons: bug fix, use correct point index (and add support for multi-part and multi-point)
changes.md: document renaming of tools in 9.13.0