xopto.mcbase.mcpf.lut module

class Lut(params: list, lut: numpy.ndarray)[source]

Bases: xopto.mcbase.mcpf.pfbase.PfBase

Lookup table-based scattering phase function constructor. Lookup table is used for efficient computation of deflection angle cosines. A nonlinear transformation is used to compute linear lookup table (floating point) index from a uniform random number F:

index = 0.5*(params[0]/(F - params[2]) - params[1] + 1.0)*data.size
Parameters

  • params (list, tuple or ndarray vector of 3 float) – Nonlinear index transformation function parameters provided as an array of size 3.

  • lut (np.ndarray vector) – Lookup table data.

Note

The offset of the first lookup table entry is stored in the 45th user-defined scattering phase function parameter. The lookup table size is stored in the 4th user-defined scattering phase function parameter.

static cl_declaration(mc: xopto.mcbase.mcobject.McObject) → str[source]

OpenCL declarations of the scattering phase function.

static cl_implementation(mc: xopto.mcbase.mcobject.McObject) → str[source]

OpenCL implementation of the scattering phase function.

static cl_options(mc: xopto.mcbase.mcobject.McObject) → List[Tuple[str, str]][source]
cl_pack(mc: xopto.mcbase.mcobject.McObject, target: Optional[xopto.cl.cltypes.Structure] = None) → xopto.cl.cltypes.Structure[source]

Fills the an OpenCL cltypes.Structure (target) with the data required by the Monte Carlo simulator. See the cl_type() method for a detailed list of fields.

Note

Calls the Mc.pack_fp_lut() method to pack the lookup table array data.

Parameters
Returns

target – Target structure received as an input argument or a new instance of ClLut if the input argument target is None.

Return type

cltypes.Structure

static cl_type(mc: xopto.mcbase.mcobject.McObject) → xopto.cl.cltypes.Structure[source]

Returns an OpenCL structure that can be passed to the Monte carlo simulator.

Parameters

mc (McObject) – A Monte Carlo simulator instance.

Returns

struct – A structure type that represents the scattering phase function in the Monte Carlo kernel.

The returned structure type implements the following fields:

  • a: mc_fp_t

    Parameter of the nonlinear lookup table index transformation.

  • b: mc_fp_t

    Parameter of the nonlinear lookup table index transformation.

  • c: mc_fp_t

    Parameter of the nonlinear lookup table index transformation.

  • offset: mc_int_t

    Location of the lookup table as an offset from the start of the lookup table buffer.

  • size: mc_int_t

    Number of entries in the lookup table.

Return type

cltypes.Structure

Note

Note that this implementation of the lookup table uses the following nonlinear transformation to compute the lookup table index from a uniform random number \xi \in [0, 1].

index &= \frac{1}{2}(\frac{a}/{\xi - c} - b + 1)N,

where a, b, c are the parameters of the nonlinear index transformation and N is the size of the lookup table

property lut: numpy.ndarray

Lookup table object or None.

property offset: int

Offset of the first element in the lookup table.

property params: list

Lookup table index transformation parameters.

property size: int

Lookup table size.

todict() → dict[source]

Export object to a dict.

class LutEx(pftype: xopto.mcbase.mcpf.pfbase.PfBase, pfargs: list, lutsize: int = 2000, **kwargs)[source]

Bases: xopto.mcbase.mcpf.lut.Lut

Creates a Monte Carlo lookup table-based scattering phase function instance from a standard scattering phase function instance (xopto.pf.PfBase subclass).

Parameters

  • pftype (PfBase subclass or str) – Scattering phase function type. Use one defined in the xopto.pf module.

  • pfargs (list, tuple) – A list of scattering phase function parameters passed to the pftype.

  • lutsize (int) – Number of elements in the lookup table.

  • kwargs (dict) – Additional keyword arguments passed to the lut method of the scattering phase function as pftype(*pfargs).lut(lutsize, **kwargs)

property pf: xopto.mcbase.mcpf.pfbase.PfBase

Scattering phase function object that was used to create a lookup table.

property pfargs: tuple

A tuple of scattering phase function arguments.

todict() → dict[source]

Export object to a dict.