I was able to compile WRF3.8.1 and WPS3.8.1 on a RaspberryPi4 8GB ... 128 GB SD card... and it worked to the point of a metgrid error noting missing a surface data element...GFS change. So I understood that WPS4.1 would correct that an be backward compatible. (Only reason for 3.8.1 was that I had seen it succesfully run on a RaspberryPi.) I downloaded geog_high_res_mandatory to replace geo_complete to be compatible with 4.1. I could make the geogrid, but ungrib would not compile. My intmath.f file from 4.1 already has the changes noted in #119. Could this be related to the RaspberryPi (arm7) environment, or have I missed something (likely)? Attached is the compile.log from attempting to compile ungrib, and screen captures of my intmath.f file. Let me know what else I should provide. Thanks in advance... Steve (up to the glitch... RPI4 with 8GB of RAM was doing well. I have a second RPI4 8GB to make a small cluster. If this works out, I may add more RPIs).