Say we have the default region 0, some region 1, and some region 2 that is within region 1. If we set Ku1 = 1e4, then do Ku1.SetRegion(1, 1e5), then region 2 will take 1e4. If, on the other hand, we do Ku1.SetRegion(0, 1e4) and `Ku1.SetRegion(1e5), then region 2 will take 0. To get region 2 to match with region 1, we have to separately call Ku1.SetRegion(1, 1e5) and Ku1.SetRegion(2, 1e5).

ffmpeg -framerate 25 -i Data/m%06d.png -r 25 -pix_fmt yuv420p mag.mp4

1. In the cuda/ directory, add the required .cu file
2. Run make to generate the wrapper and .ptx files (may need to specify some options if it does not work for some compute capabilities, see the comments in cuda/Makefile)
3. Add the corresponding .go files, which calls the function defined in the automatically generated wrapper file (if this is not clear, look at existing examples, e.g. with cuda/exchange.go)
4. Add a file in the engine/ directory (typically this is not necessary, but engine/exchange.go should be modified accordingly)
5. Add the new field to the effective field in engine/effectivefield.go (assuming it wasn't just a simple modification of e.g. the exchange field).
6. cd to cmd/mumax3 and run go install. The binary will be in $GOPATH/bin

Probably forgot to set the saturation magnetization Msat.