EvalTo method for magnetic parameters

[Chris317]

Issue details

hello!
May I ask what is the difference in the required Slice for the EvalTo method between B-ext and alpha? Why can Slice constructed with newVectorMask run normally for B_ext, but not for alpha? How to construct Slice with magnetic parameters?

For example:
mask := newVectorMask(Nx, Ny, 1)
for i:=0; i<Nx; i++{
for j:=0; j<Ny; j++{
r := index2coord(i, j, 0)
x := r.X()
y := r.Y()
Bz := exp(-pow((x-500e-9)/100e-9, 2)) * exp(-pow(y/250e-9, 2))
mask.setVector(i, j, 0, vector(0, 0, Bz))
}
}
B_ext.EvalTo(mask)
The above code can run normally

However,
mask := newVectorMask(Nx, Ny, 1)
for i:=0; i<Nx; i++{
for j:=0; j<Ny; j++{
r := index2coord(i, j, 0)
x := r.X()
y := r.Y()
Bz := exp(-pow((x-500e-9)/100e-9, 2)) * exp(-pow(y/250e-9, 2))
mask.SetScalar(i, j, 0, 0.1)
}
}
alpha.EvalTo(mask)
panic: slice not accessible by GPU

[jplauzie]

Hi,

This sort of question would be better suited to the mailing list here. That said, material parameters like alpha need to be set using regions. You cannot simply set an arbitrary mask. For details on how regions work, you can check the examples page, or the original mumax paper.

(Also, it is not relevant, but even if this did work, you would need to use NewScalarMask, not NewVectorMask. Alpha is a scalar, not a vector)

Best,
Josh L.