Simulator data types

Data types can be used to customize the OpenCL kernel of the Monte Carlo simulator. The following 4 data types of the kernel can be customized:

1. Default integer types

   • McInt32 - 32-bit integer

   • McInt64 - 64-bit integer

2. Photon packet accumulator types

   • McAccu32 - 32-bit unsigned integer

   • McAccu64 - 64-bit unsigned integer

3. Floating point types and computational precision

   • McFloat - single precision floating-point

   • McDouble - double precision floating-point

4. Photon packet counter types

   • McCnt32 - 32-bit unsigned integer counter

   • McCnt64 - 64-bit unsigned integer counter

The 4 data types are passed to the xopto:mcml.mc.Mc() constructor as an instance of xopto.mcbase.mctypes.McDataTypes. Even though any combination of the 4 data types can be used, the preconfigured sets of data types will be likely sufficient for the vast majority of applications:

• xopto.mcbase.mctypes.McDataTypesSingle - default set of types (single precision floating-point arithmetics, 32-bit photon packet counter)

  • McInt32 - 32-bit integer

  • McCnt32 - 32-bit unsigned photon packet counter

  • McAccu64 - 64-bit unsigned weight accumulators

  • McFloat - single precision floating-point arithmetics

• xopto.mcbase.mctypes.McDataTypesSingleCnt64 (single precision floating-point arithmetics, 64-bit photon packet counter)

  • McInt32 - 32-bit integer

  • McCnt64 - 64-bit unsigned photon packet counter

  • McAccu64 - 64-bit unsigned weight accumulators

  • McFloat - single precision floating-point arithmetics

• xopto.mcbase.mctypes.McDataTypesDouble (double precision floating-point arithmetics, 32-bit photon packet counter)

  • McInt32 - 32-bit integer

  • McCnt32 - 32-bit unsigned photon packet counter

  • McAccu64 - 64-bit unsigned weight accumulators

  • McDouble - double precision floating-point arithmetics

• xopto.mcbase.mctypes.McDataTypesDoubleCnt64 (double precision floating-point arithmetics, 64-bit photon packet counter)

  • McInt32 - 32-bit integer

  • McCnt64 - 32-bit unsigned photon packet counter

  • McAccu64 - 64-bit unsigned weight accumulators

  • McDouble - double precision floating-point arithmetics

Note

The 32-bit photon packet weight accumulators McAccu32 should be avoided, since they can overflow even for simulations with a small number of photon packets.

Single precision floating-point arithmetics McFloat should be sufficient for most application. Note that double precision floating-point arithmetics McDouble is significantly slower on GPU devices.

If more that 4,294,967,295 photon packets need to be simulated in a single run of the Monte Carlo simulator, use a 64-bit photon packet counter McCnt64. The performance penalty will depend on the OpenCL device support for 64-bit atomic operations (cl_khr_int64_base_atomics OpenCL extension)