1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
package engine
import (
"github.com/mumax/3/cuda"
"github.com/mumax/3/util"
)
type Euler struct{}
// Euler method, can be used as solver.Step.
func (*Euler) Step() {
y := M.Buffer()
dy0 := cuda.Buffer(VECTOR, y.Size())
defer cuda.Recycle(dy0)
torqueFn(dy0)
setMaxTorque(dy0)
// Adaptive time stepping: treat MaxErr as the maximum magnetization delta
// (proportional to the error, but an overestimation for sure)
var dt float32
if FixDt != 0 {
Dt_si = FixDt
dt = float32(Dt_si * GammaLL)
} else {
dt = float32(MaxErr / LastTorque)
Dt_si = float64(dt) / GammaLL
}
util.AssertMsg(dt > 0, "Euler solver requires fixed time step > 0")
setLastErr(float64(dt) * LastTorque)
cuda.Madd2(y, y, dy0, 1, dt) // y = y + dt * dy
M.normalize()
Time += Dt_si
NSteps++
}
func (*Euler) Free() {}
|
