engine

package
v3.4.0-beta1+incompatible Latest Latest
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 Go to latest Published: Jan 20, 2014 License: GPL-3.0 Imports: 32 Imported by: 0

Documentation

Index

Constants

View Source 
const (
	TILE   = 2           // tile size in grains
	LAMBDA = TILE * TILE // expected grains per tile
)
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const (
	EULER = 1
	HEUN  = 2
)
View Source 
const (
	X = 0
	Y = 1
	Z = 2
)
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const (
	SCALAR = 1
	VECTOR = 3
)
View Source 
const DEFAULT_KERNEL_ACC = 6

Default accuracy setting for demag kernel. TODO: variable?

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const NREGION = 256 // maximum number of regions. (!) duplicated in CUDA
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const VERSION = "mumax3.4.0 BETA1"

Variables

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var (
	Ku1, Kc1              ScalarParam // uniaxial and cubic anis constants
	AnisU, AnisC1, AnisC2 VectorParam // unixial and cubic anis axes

	B_anis     vAdder     // field due to uniaxial anisotropy (T)
	E_anis     *GetScalar // Anisotorpy energy
	Edens_anis sAdder     // Anisotropy energy density
)

Anisotropy variables

View Source 
var (
	Msat        ScalarParam
	Bsat        derivedParam
	M_full      vSetter
	B_demag     vSetter
	E_demag     *GetScalar
	Edens_demag sAdder
	EnableDemag = true // enable/disable demag field

)

demag variables

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var (
	E_total     = NewGetScalar("E_total", "J", "Total energy", GetTotalEnergy)
	Edens_total sSetter
)
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var (
	Aex    ScalarParam // Exchange stiffness
	Dex    ScalarParam // DMI strength
	B_exch vAdder      // exchange field (T) output handle

	E_exch     *GetScalar
	Edens_exch sAdder
)
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var (
	BubblePos   = NewGetVector("ext_bubblepos", "m", "Bubble core position", bubblePos)
	BubbleDist  = NewGetScalar("ext_bubbledist", "m", "Bubble traveled distance", bubbleDist)
	BubbleSpeed = NewGetScalar("ext_bubblespeed", "m/s", "Bubble velocity", bubbleSpeed)
)
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var (
	MFM        sSetter
	MFMLift    numberParam
	MFMTipSize numberParam
)
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var (
	Solver = NewSolver(Torque.Set, M.normalize, 1e-15, mag.Gamma0, HeunStep)
	Time   float64 // time in seconds

	Inject = make(chan func()) // injects code in between time steps. Used by web interface.

)
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var (
	TotalShift                      float64                        // accumulated window shift (X) in meter
	ShiftMagL, ShiftMagR            data.Vector                    // when shifting m, put these value at the left/right edge.
	ShiftM, ShiftGeom, ShiftRegions bool        = true, true, true // should shift act on magnetization, geometry, regions?
)
View Source 
var (
	Temp ScalarParam

	B_therm     vAdder
	E_therm     *GetScalar
	Edens_therm sAdder
)
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var (
	Alpha        ScalarParam
	Xi           ScalarParam
	Pol          ScalarParam
	Lambda       ScalarParam
	EpsilonPrime ScalarParam
	FixedLayer   VectorParam
	Torque       vSetter    // total torque in T
	LLTorque     vSetter    // Landau-Lifshitz torque/γ0, in T
	STTorque     vAdder     // Spin-transfer torque/γ0, in T
	J            excitation // Polarized electrical current density
	MaxTorque    *GetScalar
)
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var (
	B_ext        excitation
	E_Zeeman     *GetScalar
	Edens_zeeman sAdder
)
View Source 
var B_eff vSetter // total effective field
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var CorePos = NewGetVector("ext_corepos", "m", "Vortex core position", corePos)
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var (
	DWPos = NewGetScalar("ext_dwpos", "m", "Position of the simulation window while following a domain wall", GetShiftPos) // TODO: make more accurate
)
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var (
	DWSpeed = NewGetScalar("ext_dwspeed", "m/s", "Speed of the simulation window while following a domain wall", getShiftSpeed)
)

used for speed

View Source 
var DWTiltPMA = NewGetScalar("ext_dwtilt", "rad", "PMA domain wall tilt", dwTiltPMA)

PMA domain wall tilt assuming straight wall.

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var (
	GUI = guistate{Quants: make(map[string]Quantity), Params: make(map[string]Param)}
)

global GUI state stores what is currently shown in the web page.

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var M magnetization // reduced magnetization (unit length)
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var OD = "./" // Output directory
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var StartTime = time.Now()
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var Table = *newTable("table") // output handle for tabular data (average magnetization etc.)
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var Timeout = 3 * time.Second

exit finished simulation this long after browser was closed

View Source 
var UNAME = VERSION + " " + runtime.GOOS + "_" + runtime.GOARCH + " " + runtime.Version() + " (" + runtime.Compiler + ")"
View Source 
var World = script.NewWorld()

holds the script state (variables etc)

Functions

func AddAnisotropyField 

func AddAnisotropyField(dst *data.Slice)

Add the anisotropy field to dst

func AddExchangeField 

func AddExchangeField(dst *data.Slice)

Adds the current exchange field to dst

func AddSTTorque 

func AddSTTorque(dst *data.Slice)

Adds the current spin transfer torque to dst

func AddThermalField 

func AddThermalField(dst *data.Slice)

func AutoSave 

func AutoSave(quant Quantity, period float64)

Register quant to be auto-saved every period. period == 0 stops autosaving.

func CenterWall 

func CenterWall(magComp int)

This post-step function centers the simulation window on a domain wall between up-down (or down-up) domains (like in perpendicular media). E.g.: 

PostStep(CenterPMAWall)

func Close 

func Close()

Cleanly exits the simulation, assuring all output is flushed.

func Comp 

func Comp(parent Averagable, c int) *comp

func Const 

func Const(e script.Expr) bool

checks if a script expression contains t (time)

func DeclConst 

func DeclConst(name string, value float64, doc string)

Add a constant to the script world

func DeclFunc 

func DeclFunc(name string, f interface{}, doc string)

Add a function to the script world

func DeclLValue 

func DeclLValue(name string, value script.LValue, doc string)

Add an LValue to the script world. Assign to LValue invokes SetValue()

func DeclROnly 

func DeclROnly(name string, value interface{}, doc string)

Add a read-only variable to the script world. It can be changed, but not by the user.

func DeclVar 

func DeclVar(name string, value interface{}, doc string)

Add a (pointer to) variable to the script world

func DefRegion 

func DefRegion(id int, s Shape)

Define a region with id (0-255) to be inside the Shape.

func DefRegionCell 

func DefRegionCell(id int, x, y, z int)

func DoOutput 

func DoOutput()

Periodically called by run loop to save everything that's needed at this time.

func Download 

func Download(q Quantity) *data.Slice

Download a quantity to host, or just return its data when already on host.

func EulerStep 

func EulerStep(s *solver, y *data.Slice)

Euler method, can be used as solver.Step.

func Eval 

func Eval(code string)

func EvalFile 

func EvalFile(code *script.BlockStmt)

evaluate code, exit on error (behavior for input files)

func Expect 

func Expect(msg string, have, want, maxError float64)

Test if have lies within want +/- maxError, and print suited message.

func ExpectV 

func ExpectV(msg string, have, want data.Vector, maxErr float64)

func Fprintln 

func Fprintln(filename string, msg ...interface{})

Append msg to file. Used to write aggregated output of many simulations in one file.

func GetAnisotropyEnergy 

func GetAnisotropyEnergy() float64

func GetDemagEnergy 

func GetDemagEnergy() float64

Returns the current demag energy in Joules.

func GetExchangeEnergy 

func GetExchangeEnergy() float64

Returns the current exchange energy in Joules. Note: the energy is defined up to an arbitrary constant, ground state energy is not necessarily zero or comparable to other simulation programs.

func GetMaxTorque 

func GetMaxTorque() float64

Gets

func GetShiftPos 

func GetShiftPos() float64

func GetThermalEnergy 

func GetThermalEnergy() float64

func GetTotalEnergy 

func GetTotalEnergy() float64

Returns the total energy in J.

func GetZeemanEnergy 

func GetZeemanEnergy() float64

func HeunStep 

func HeunStep(s *solver, y *data.Slice)

Adaptive Heun method, can be used as solver.Step

func Index2Coord 

func Index2Coord(ix, iy, iz int) data.Vector

converts cell index to coordinate, internal coordinates

func Info 

func Info(nComp int, name, unit string) info

func InjectAndWait 

func InjectAndWait(task func())

inject code into engine and wait for it to complete.

func KeepAlive 

func KeepAlive() time.Time

func LoadFile 

func LoadFile(fname string) *data.Slice

Read a magnetization state from .dump file.

func LogInput 

func LogInput(msg ...interface{})

func LogOutput 

func LogOutput(msg ...interface{})

func Mesh 

func Mesh() *data.Mesh

func NewSlice 

func NewSlice(ncomp, Nx, Ny, Nz int) *data.Slice

Returns a new new slice (3D array) with given number of components and size.

func NewSolver 

func NewSolver(torqueFn func(dst *data.Slice), postStep func(), dt_si, dt_mul float64, step func(*solver, *data.Slice)) solver

func OverrideExchangeLength 

func OverrideExchangeLength(region1, region2 int, exlen float64)

Defines the exchange coupling between different regions by specifying the exchange length of the interaction between them. 

lex := sqrt(2*Aex / Msat)

In case of different materials it is not always clear what the exchange between them should be, especially if they have different Msat. By specifying the exchange length, it is up to the user to decide which Msat to use. A negative length may be specified to obtain antiferromagnetic coupling.

func PostStep 

func PostStep(f func())

Register function f to be called after every time step. Typically used, e.g., to manipulate the magnetization.

func RemoveLRSurfaceCharge 

func RemoveLRSurfaceCharge(region int, mxLeft, mxRight float64)

For a nanowire magnetized in-plane, with mx = mxLeft on the left end and mx = mxRight on the right end (both -1 or +1), add a B field needed to compensate for the surface charges on the left and right edges. This will mimic an infinitely long wire.

func Run 

func Run(seconds float64)

Run the simulation for a number of seconds.

func RunInteractive 

func RunInteractive()

Enter interactive mode. Simulation is now exclusively controlled by web GUI

func RunWhile 

func RunWhile(condition func() bool)

Runs as long as condition returns true.

func Save 

func Save(q Quantity)

Save once, with auto file name

func SaveAs 

func SaveAs(q Quantity, fname string)

Save under given file name (transparant async I/O).

func Serve 

func Serve(port string)

Start web gui on given port, blocks.

func SetCellSize 

func SetCellSize(cx, cy, cz float64)

func SetDemagField 

func SetDemagField(dst *data.Slice)

Sets dst to the current demag field

func SetEffectiveField 

func SetEffectiveField(dst *data.Slice)

Sets dst to the current effective field (T).

func SetGeom 

func SetGeom(s Shape)

func SetGridSize 

func SetGridSize(Nx, Ny, Nz int)

func SetLLTorque 

func SetLLTorque(dst *data.Slice)

Sets dst to the current Landau-Lifshitz torque

func SetMFM 

func SetMFM(dst *data.Slice)

func SetMFull 

func SetMFull(dst *data.Slice)

Sets dst to the full (unnormalized) magnetization in A/m

func SetMesh 

func SetMesh(Nx, Ny, Nz int, cellSizeX, cellSizeY, cellSizeZ float64, pbcx, pbcy, pbcz int)

Set the simulation mesh to Nx x Ny x Nz cells of given size. Can be set only once at the beginning of the simulation. TODO: dedup arguments from globals

func SetOD 

func SetOD(od string, force bool)

SetOD sets the output directory where auto-saved files will be stored. The -o flag can also be used for this purpose.

func SetPBC 

func SetPBC(nx, ny, nz int)

func SetSolver 

func SetSolver(typ int)

func SetTorque 

func SetTorque(dst *data.Slice)

Sets dst to the current total torque

func SetTotalEdens 

func SetTotalEdens(dst *data.Slice)

func Shift 

func Shift(dx int)

shift the simulation window over dx cells in X direction

func Steps 

func Steps(n int)

Run the simulation for a number of steps.

func TableAdd 

func TableAdd(col TableData)

func TableAutoSave 

func TableAutoSave(period float64)

func TableSave 

func TableSave()

func ThermSeed 

func ThermSeed(seed int)

Seeds the thermal noise generator

func Vector 

func Vector(x, y, z float64) data.Vector

Constructs a vector

func Voronoi 

func Voronoi(grainsize float64, numRegions, seed int)

Types

type Averagable 

type Averagable interface {
	Quantity
	// contains filtered or unexported methods
}

type Config 

type Config func(x, y, z float64) data.Vector

Magnetic configuration returns m vector for position (x,y,z)

func AntiVortex 

func AntiVortex(circ, pol int) Config

func Antiskyrmion 

func Antiskyrmion(charge, pol int) Config

func RandomMag 

func RandomMag() Config

func Skyrmion 

func Skyrmion(charge, pol int) Config

func TwoDomain 

func TwoDomain(mx1, my1, mz1, mxwall, mywall, mzwall, mx2, my2, mz2 float64) Config

Make a 2-domain configuration with domain wall. (mx1, my1, mz1) and (mx2, my2, mz2) are the magnetizations in the left and right domain, respectively. (mxwall, mywall, mzwall) is the magnetization in the wall. The wall is smoothed over a few cells so it will easily relax to its ground state. E.g.: 

TwoDomain(1,0,0,  0,1,0,  -1,0,0) // head-to-head domains with transverse (Néel) wall
TwoDomain(1,0,0,  0,0,1,  -1,0,0) // head-to-head domains with perpendicular (Bloch) wall
TwoDomain(0,0,1,  1,0,0,   0,0,-1)// up-down domains with Bloch wall

func Uniform 

func Uniform(mx, my, mz float64) Config

Returns a uniform magnetization state. E.g.: 

M = Uniform(1, 0, 0)) // saturated along X

func Vortex 

func Vortex(circ, pol int) Config

Make a vortex magnetization with given circulation and core polarization (+1 or -1). The core is smoothed over a few exchange lengths and should easily relax to its ground state.

func VortexWall 

func VortexWall(mleft, mright float64, circ, pol int) Config

Make a vortex wall configuration.

func (Config) Add 

func (c Config) Add(weight float64, other Config) Config

func (Config) RotZ 

func (c Config) RotZ(θ float64) Config

Rotates the configuration around the Z-axis, over θ radians.

func (Config) Scale 

func (c Config) Scale(sx, sy, sz float64) Config

Scale returns a scaled copy of configuration c.

func (Config) Transl 

func (c Config) Transl(dx, dy, dz float64) Config

Transl returns a translated copy of configuration c. E.g.: 

M = Vortex(1, 1).Transl(100e-9, 0, 0)  // vortex with center at x=100nm

type DataTable 

type DataTable struct {
	*bufio.Writer
	// contains filtered or unexported fields
}

func (*DataTable) Add 

func (t *DataTable) Add(output TableData)

func (*DataTable) NComp 

func (i *DataTable) NComp() int

func (*DataTable) Name 

func (i *DataTable) Name() string

func (*DataTable) Save 

func (t *DataTable) Save()

func (*DataTable) Unit 

func (i *DataTable) Unit() string

type GetScalar 

type GetScalar struct {
	// contains filtered or unexported fields
}

func NewGetScalar 

func NewGetScalar(name, unit, doc string, get func() float64) *GetScalar

INTERNAL

func (*GetScalar) Average 

func (g *GetScalar) Average() float64

func (*GetScalar) Get 

func (g *GetScalar) Get() float64

type GetVector 

type GetVector struct {
	// contains filtered or unexported fields
}

func NewGetVector 

func NewGetVector(name, unit, doc string, get func() []float64) *GetVector

INTERNAL

func (*GetVector) Average 

func (g *GetVector) Average() data.Vector

func (*GetVector) Get 

func (g *GetVector) Get() data.Vector

type Param 

type Param interface {
	NComp() int
	Name() string
	Unit() string

	IsUniform() bool
	// contains filtered or unexported methods
}

displayable quantity in GUI Parameters section

type Quantity 

type Quantity interface {
	Slice() (q *data.Slice, recycle bool) // get quantity data (GPU or CPU), indicate need to recycle
	NComp() int
	Name() string
	Unit() string
	Mesh() *data.Mesh
}

Any space-dependent quantity

type Regions 

type Regions struct {
	// contains filtered or unexported fields
}

stores the region index for each cell

func (*Regions) Gpu 

func (r *Regions) Gpu() *cuda.Bytes

Get the region data on GPU

func (*Regions) HostArray 

func (r *Regions) HostArray() [][][]byte

func (*Regions) HostList 

func (r *Regions) HostList() []byte

func (*Regions) Mesh 

func (r *Regions) Mesh() *data.Mesh

func (*Regions) NComp 

func (i *Regions) NComp() int

func (*Regions) Name 

func (i *Regions) Name() string

func (*Regions) SetCell 

func (r *Regions) SetCell(ix, iy, iz int, region int)

Set the region of one cell TODO dedup

func (*Regions) Slice 

func (r *Regions) Slice() (*data.Slice, bool)

Get returns the regions as a slice of floats, so it can be output.

func (*Regions) Unit 

func (i *Regions) Unit() string

type ScalarParam 

type ScalarParam struct {
	// contains filtered or unexported fields
}

specialized param with 1 component

func (*ScalarParam) Average 

func (p *ScalarParam) Average() float64

func (*ScalarParam) Child 

func (p *ScalarParam) Child() []script.Expr

func (*ScalarParam) Eval 

func (p *ScalarParam) Eval() interface{}

func (*ScalarParam) GetRegion 

func (p *ScalarParam) GetRegion(region int) float64

func (*ScalarParam) InputType 

func (p *ScalarParam) InputType() reflect.Type

func (*ScalarParam) IsUniform 

func (p *ScalarParam) IsUniform() bool

func (*ScalarParam) Mesh 

func (p *ScalarParam) Mesh() *data.Mesh

func (*ScalarParam) Name 

func (p *ScalarParam) Name() string

func (*ScalarParam) Region 

func (p *ScalarParam) Region(r int) *sOneReg

func (*ScalarParam) Set 

func (p *ScalarParam) Set(v float64)

func (*ScalarParam) SetRegion 

func (p *ScalarParam) SetRegion(region int, f script.ScalarFunction)

func (*ScalarParam) SetValue 

func (p *ScalarParam) SetValue(v interface{})

func (*ScalarParam) Type 

func (p *ScalarParam) Type() reflect.Type

func (*ScalarParam) Unit 

func (p *ScalarParam) Unit() string

type Shape 

type Shape func(x, y, z float64) bool

geometrical shape for setting sample geometry

func Cell 

func Cell(ix, iy, iz int) Shape

Single cell with given index

func Circle 

func Circle(diam float64) Shape

func Cuboid 

func Cuboid(sidex, sidey, sidez float64) Shape

3D Rectangular slab with given sides.

func Cylinder 

func Cylinder(diam, height float64) Shape

cylinder along z.

func Ellipse 

func Ellipse(diamx, diamy float64) Shape

func Ellipsoid 

func Ellipsoid(diamx, diamy, diamz float64) Shape

Ellipsoid with given diameters

func ImageShape 

func ImageShape(fname string) Shape

func Layers 

func Layers(a, b int) Shape

Cell layers #a (inclusive) up to #b (exclusive).

func Rect 

func Rect(sidex, sidey float64) Shape

2D Rectangle with given sides.

func Universe 

func Universe() Shape

func XRange 

func XRange(a, b float64) Shape

All cells with x-coordinate between a and b

func YRange 

func YRange(a, b float64) Shape

All cells with y-coordinate between a and b

func ZRange 

func ZRange(a, b float64) Shape

All cells with z-coordinate between a and b

func (Shape) Add 

func (a Shape) Add(b Shape) Shape

Union of shapes a and b (logical OR).

func (Shape) Intersect 

func (a Shape) Intersect(b Shape) Shape

Intersection of shapes a and b (logical AND).

func (Shape) Inverse 

func (s Shape) Inverse() Shape

Inverse (outside) of shape (logical NOT).

func (Shape) Repeat 

func (s Shape) Repeat(periodX, periodY, periodZ float64) Shape

Infinitely repeats the shape with given period in x, y, z. A period of 0 or infinity means no repetition.

func (Shape) RotX 

func (s Shape) RotX(θ float64) Shape

Rotates the shape around the X-axis, over θ radians.

func (Shape) RotY 

func (s Shape) RotY(θ float64) Shape

Rotates the shape around the Y-axis, over θ radians.

func (Shape) RotZ 

func (s Shape) RotZ(θ float64) Shape

Rotates the shape around the Z-axis, over θ radians.

func (Shape) Scale 

func (s Shape) Scale(sx, sy, sz float64) Shape

Scale returns a scaled copy of the shape.

func (Shape) Sub 

func (a Shape) Sub(b Shape) Shape

Removes b from a (logical a AND NOT b)

func (Shape) Transl 

func (s Shape) Transl(dx, dy, dz float64) Shape

Transl returns a translated copy of the shape.

func (Shape) Xor 

func (a Shape) Xor(b Shape) Shape

Logical XOR of shapes a and b

type TableData 

type TableData interface {
	Name() string
	Unit() string
	NComp() int
	// contains filtered or unexported methods
}

can be saved in table

type VectorParam 

type VectorParam struct {
	// contains filtered or unexported fields
}

vector input parameter, settable by user

func (*VectorParam) Average 

func (p *VectorParam) Average() data.Vector

func (*VectorParam) Child 

func (p *VectorParam) Child() []script.Expr

func (*VectorParam) Comp 

func (p *VectorParam) Comp(c int) *comp

func (*VectorParam) Eval 

func (p *VectorParam) Eval() interface{}

func (*VectorParam) GetRegion 

func (p *VectorParam) GetRegion(region int) [3]float64

func (*VectorParam) InputType 

func (p *VectorParam) InputType() reflect.Type

func (*VectorParam) IsUniform 

func (p *VectorParam) IsUniform() bool

func (*VectorParam) Mesh 

func (p *VectorParam) Mesh() *data.Mesh

func (*VectorParam) Name 

func (p *VectorParam) Name() string

func (*VectorParam) Region 

func (p *VectorParam) Region(r int) *vOneReg

func (*VectorParam) SetRegion 

func (p *VectorParam) SetRegion(region int, f script.VectorFunction)

func (*VectorParam) SetValue 

func (p *VectorParam) SetValue(v interface{})

func (*VectorParam) Type 

func (p *VectorParam) Type() reflect.Type

func (*VectorParam) Unit 

func (p *VectorParam) Unit() string

Source Files

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