: communicator(comm)

{

MPI_Comm_rank(communicator, &world_rank);

MPI_Comm_size(communicator, &world_size);

{

unsigned short local_max = 0;

unsigned short local_min = USHRT_MAX;

size_t local_size = local_n0 * dims[1] * dims[2];

// Find the local maximum and minimum material indices

for (size_t i = 0; i < local_size; i++) {

unsigned short val = static_cast<unsigned short>(ms[i]);

if (val > local_max) {

local_max = val;

}

if (val < local_min) {

local_min = val;

}

}

// Find the global maximum and minimum material indices

unsigned short global_max, global_min;

MPI_Allreduce(&local_max, &global_max, 1, MPI_UNSIGNED_SHORT, MPI_MAX, communicator);

MPI_Allreduce(&local_min, &global_min, 1, MPI_UNSIGNED_SHORT, MPI_MIN, communicator);

if (global_min != 0)

throw std::invalid_argument("Microstructure phase IDs must start at 0");

// Calculate total number of materials

n_mat = global_max - global_min + 1;

Log::logger().info("# Number of materials: {} (from {} to {})", n_mat, global_min, global_max);

Log::logger().info("# Volume fractions");

// Using dynamic allocation for arrays since we don't know size at compile time

std::vector<long> vol_frac(n_mat, 0);

std::vector<double> v_frac(n_mat, 0.0);

for (size_t i = 0; i < local_size; i++) {

unsigned short val = static_cast<unsigned short>(ms[i]);

int index = val - global_min; // Adjust index to start from 0

vol_frac[index]++;

}

for (int i = 0; i < n_mat; i++) {

long vf;

MPI_Allreduce(&(vol_frac[i]), &vf, 1, MPI_LONG, MPI_SUM, communicator);

v_frac[i] = double(vf) / double(dims[0] * dims[1] * dims[2]);

Log::logger().info("# material {:4} vol. frac. {:10.4f}% ", static_cast<unsigned int>(i) + global_min, 100. * v_frac[i]);

}

{

try {

ifstream i(input_fn);

json j;

i >> j;

inputJson = j; // Store complete input JSON for MaterialManager

microstructure = j["microstructure"];

std::snprintf(ms_filename, sizeof(ms_filename), "%s", microstructure["filepath"].get<std::string>().c_str());

// dataset name handling

const auto tmp_str = microstructure["datasetname"].get<std::string>();

if (tmp_str.empty())

throw std::invalid_argument("datasetname must not be empty and must refer to a valid HDF5 path");

// Ensure absolute HDF5 path, leading slash

std::snprintf(ms_datasetname, sizeof(ms_datasetname), "%s%s", tmp_str.front() == '/' ? "" : "/", tmp_str.c_str());

L = microstructure["L"].get<vector<double>>();

if (j.contains("results_prefix")) {

std::snprintf(results_prefix, sizeof(results_prefix), "%s", j["results_prefix"].get<std::string>().c_str());

} else {

strcpy(results_prefix, "");

}

// Construct dataset_name as "<ms_datasetname>_results/<results_prefix>"

std::snprintf(dataset_name, sizeof(dataset_name), "%s_results/%s", ms_datasetname, results_prefix);

errorParameters = j["error_parameters"];

TOL = errorParameters["tolerance"].get<double>();

n_it = j["n_it"].get<int>();

extrapolate_displacement = j.value("extrapolate_displacement", extrapolate_displacement);

if (j.contains("linesearch_parameters")) {

ls_max_iter = j["linesearch_parameters"].value("max_iter", ls_max_iter);

ls_tol = j["linesearch_parameters"].value("tol", ls_tol);

if (ls_max_iter < 1 || ls_tol <= 0.0)

throw std::invalid_argument("linesearch_parameters: max_iter >= 1 and tol > 0 required");

}

problemType = j["problem_type"].get<string>();

method = j["method"].get<string>();

// Parse strain_type (optional, defaults to "small")

if (j.contains("strain_type")) {

strain_type = j["strain_type"].get<string>();

if (strain_type != "small" && strain_type != "large") {

throw std::invalid_argument("strain_type must be either 'small' or 'large'");

}

} else {

strain_type = "small"; // Default to small strain

}

// Parse FE_type (optional, defaults to "HEX8")

if (j.contains("FE_type")) {

FE_type = j["FE_type"].get<string>();

if (FE_type != "HEX8" && FE_type != "HEX8R" && FE_type != "BBAR") {

throw std::invalid_argument("FE_type must be one of: 'HEX8', 'HEX8R', or 'BBAR'");

}

} else {

FE_type = "HEX8"; // Default to full integration

}

resultsToWrite = j["results"].get<vector<string>>(); // Read the results_to_write field

load_cases.clear();

const auto &ml = j["macroscale_loading"];

if (!ml.is_array())

throw std::runtime_error("macroscale_loading must be an array");

// Determine the size of loading vector based on problem type and strain formulation

int n_str;

if (problemType == "thermal") {

n_str = 3; // Temperature gradient components

} else if (strain_type == "large") {

n_str = 9; // Deformation gradient components (F11, F12, F13, F21, F22, F23, F31, F32, F33)

} else {

n_str = 6; // Small strain components (eps11, eps22, eps33, eps12, eps13, eps23)

}

for (const auto &entry : ml) {

LoadCase lc;

if (entry.is_array()) { // ---------- legacy pure-strain ----------

lc.mixed = false;

lc.g0_path = entry.get<vector<vector<double>>>();

lc.n_steps = lc.g0_path.size();

if (lc.g0_path[0].size() != static_cast<size_t>(n_str))

throw std::invalid_argument("Invalid length of loading vector: expected " +

std::to_string(n_str) + " components but got " +

std::to_string(lc.g0_path[0].size()));

} else { // ---------- mixed BC object ------------

lc.mixed = true;

lc.mbc = MixedBC::from_json(entry, n_str);

lc.n_steps = lc.mbc.F_E_path.rows();

}

load_cases.push_back(std::move(lc));

}

Log::logger().info("# microstructure file name: \t '{}'", ms_filename);

Log::logger().info("# microstructure dataset name: \t '{}'", ms_datasetname);

Log::logger().info("# strain type: \t {}", strain_type);

Log::logger().info("# problem type: \t {}", problemType);

Log::logger().info("# FE type: \t {}", FE_type);

Log::logger().info("# FANS error measure: \t {} {} error ", errorParameters["type"].get<string>(), errorParameters["measure"].get<string>());

Log::logger().info("# FANS Tolerance: \t {:10.5e}", errorParameters["tolerance"].get<double>());

Log::logger().info("# Max iterations: \t {:6}", n_it);

} catch (const std::exception &e) {

Log::logger().error("ERROR trying to read input file '{}' for FANS: {}", input_fn, e.what());

exit(10);

}

{

// no leading '/' --> exit

const char DELIMITER = '/';

if (name[0] != DELIMITER)

return;

// copy name to buffer

char buffer[4096];

strcpy(buffer, name);

char *str = buffer;

str = strchr(str + 1, DELIMITER);

while (str != NULL) {

// while another / character is found

long int l = str - buffer; // length of substring

buffer[l] = '\0'; // temporary 'end of string'

// safely create the group if needed

hid_t group;

/* Save old error handler */

herr_t (*old_func)(hid_t, void *);

void *old_client_data;

H5Eget_auto(H5E_DEFAULT, &old_func, &old_client_data);

/* Turn off error handling */

H5Eset_auto(H5E_DEFAULT, NULL, NULL);

group = H5Gopen(file, buffer, H5P_DEFAULT);

/* Restore previous error handler */

H5Eset_auto(H5E_DEFAULT, old_func, old_client_data);

if (group < 0) {

group = H5Gcreate(file, buffer, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);

}

H5Gclose(group);

buffer[l] = DELIMITER; // restore original string

str = strchr(str + 1, DELIMITER); // find next delimiter

}

{

hid_t file_id, dset_id; /* file and dataset identifiers */

hid_t filespace, memspace; /* file and memory dataspace identifiers */

hid_t data_type;

hsize_t _dims[3]; /* dataset dimensions */

hsize_t count[3]; /* hyperslab selection parameters */

hsize_t offset[3];

hid_t plist_id; /* property list identifier */

herr_t status;

// Set up file access property list with parallel I/O access

plist_id = H5Pcreate(H5P_FILE_ACCESS);

// H5Pset_fapl_mpio(plist_id, MPI_COMM_WORLD, info); // "set File Access Property List"

// Open the file collectively and release property list identifier.

file_id = H5Fopen(ms_filename, H5F_ACC_RDONLY, plist_id);

H5Pclose(plist_id);

// Create property list for collective dataset write.

// plist_id = H5Pcreate(H5P_DATASET_XFER);

// H5Pset_dxpl_mpio(plist_id, H5FD_MPIO_COLLECTIVE); // "set Data Transfer Property List" (x means transfer)

plist_id = H5P_DEFAULT;

dset_id = H5Dopen2(file_id, ms_datasetname, plist_id);

hid_t dspace = H5Dget_space(dset_id);

int rank = H5Sget_simple_extent_dims(dspace, _dims, NULL);

data_type = H5T_NATIVE_USHORT; // H5Dget_type(dset_id);

// Check if microstructure dataset has ZYX ordering through the permute_order attribute

hid_t attr_id = H5Aexists(dset_id, "permute_order") ? H5Aopen(dset_id, "permute_order", H5P_DEFAULT) : -1;

if (attr_id > 0) {

hid_t attr_type = H5Aget_type(attr_id);

char *permute_order = nullptr;

if (H5Aread(attr_id, attr_type, &permute_order) >= 0 && permute_order != nullptr) {

is_zyx = (permute_order[0] == 'z' || permute_order[0] == 'Z');

H5free_memory(permute_order);

}

H5Aclose(attr_id);

H5Tclose(attr_type);

}

if (is_zyx)

Log::logger().info("# Using Z-Y-X dimension ordering for the microstructure data");

else

Log::logger().info("# Using X-Y-Z dimension ordering for the microstructure data");

dims.resize(3);

if (is_zyx) { /* file layout Z Y X -> logical X Y Z */

dims[0] = _dims[2]; /* Nx */

dims[1] = _dims[1]; /* Ny */

dims[2] = _dims[0]; /* Nz */

} else { /* default layout X Y Z */

dims[0] = _dims[0];

dims[1] = _dims[1];

dims[2] = _dims[2];

}

l_e.resize(3);

l_e[0] = L[0] / double(dims[0]);

l_e[1] = L[1] / double(dims[1]);

l_e[2] = L[2] / double(dims[2]);

Log::logger().info("# Grid size set to [{} x {} x {}] --> {} voxels", dims[0], dims[1], dims[2], dims[0] * dims[1] * dims[2]);

Log::logger().info("# Microstructure length: [{:3.6f} x {:3.6f} x {:3.6f}]", L[0], L[1], L[2]);

Log::logger().info("# Voxel length: [{:.8f}, {:.8f}, {:.8f}]", l_e[0], l_e[1], l_e[2]);

if (dims[0] % 2 != 0)

Log::logger().warn("[ FANS3D_Grid ] WARNING: n_x is not a multiple of 2");

if (dims[1] % 2 != 0)

Log::logger().warn("[ FANS3D_Grid ] WARNING: n_y is not a multiple of 2");

if (dims[2] % 2 != 0)

Log::logger().warn("[ FANS3D_Grid ] WARNING: n_z is not a multiple of 2");

if (dims[0] / 4 < world_size)

throw std::runtime_error("[ FANS3D_Grid ] ERROR: Please decrease the number of processes or increase the grid size to ensure that each process has at least 4 boxels in the x direction.");

const ptrdiff_t n[3] = {dims[0], dims[1], dims[2] / 2 + 1};

ptrdiff_t block0 = FFTW_MPI_DEFAULT_BLOCK;

ptrdiff_t block1 = FFTW_MPI_DEFAULT_BLOCK;

// see https://fftw.org/doc/Basic-and-advanced-distribution-interfaces.html

// and https://www.fftw.org/fftw3_doc/Transposed-distributions.html

// on there it is recommended to use one of fftw's allocation functions "to ensure optimal alignment"

/* there is no documentation for this method, so here is the signature from "fftw3-mpi.h"

alloc_local = fftw_mpi_local_size_many_transposed(rank, n, hm, block0, block1, communicator, &local_n0, &local_0_start, &local_n1, &local_1_start);

if (local_n0 < 4)

throw std::runtime_error("[ FANS3D_Grid ] ERROR: Number of voxels in x-direction is less than 4 in process " + to_string(world_rank));

MPI_Barrier(communicator);

hsize_t fcount[3], foffset[3];

if (is_zyx) { /* file layout Z Y X */

fcount[0] = dims[2]; /* Nz (file-dim 0) */

fcount[1] = dims[1]; /* Ny (file-dim 1) */

fcount[2] = local_n0; /* Nx-slab (file-dim 2) */

foffset[0] = 0;

foffset[1] = 0;

foffset[2] = static_cast<hsize_t>(local_0_start);

} else { /* file layout X Y Z */

fcount[0] = local_n0;

fcount[1] = dims[1];

fcount[2] = dims[2];

foffset[0] = static_cast<hsize_t>(local_0_start);

foffset[1] = 0;

foffset[2] = 0;

}

filespace = H5Dget_space(dset_id);

H5Sselect_hyperslab(filespace, H5S_SELECT_SET, foffset, nullptr, fcount, nullptr);

/*--------------------------------------------------------------------

hsize_t memcount[3];

if (is_zyx) {

memcount[0] = fcount[0]; // Nz

memcount[1] = fcount[1]; // Ny

memcount[2] = fcount[2]; // local_n0 (X-slab)

} else {

memcount[0] = fcount[0];

memcount[1] = fcount[1];

memcount[2] = fcount[2];

}

memspace = H5Screate_simple(3, memcount, nullptr);

/*--------------------------------------------------------------------

size_t nElem = static_cast<size_t>(memcount[0]) *

static_cast<size_t>(memcount[1]) *

static_cast<size_t>(memcount[2]);

unsigned short *tmp = FANS_malloc<unsigned short>(nElem);

status = H5Dread(dset_id, data_type,

memspace, filespace, plist_id, tmp);

if (status < 0)

throw std::runtime_error("[ReadMS] H5Dread failed");

/* allocate the final buffer in logical order: Nx × Ny × Nz */

ms = FANS_malloc<unsigned short>(static_cast<size_t>(local_n0) *

static_cast<size_t>(dims[1]) *

static_cast<size_t>(dims[2]));

if (is_zyx) {

const Eigen::Index Nx = static_cast<Eigen::Index>(local_n0);

const Eigen::Index Ny = static_cast<Eigen::Index>(dims[1]);

const Eigen::Index Nz = static_cast<Eigen::Index>(dims[2]);

Eigen::TensorMap<Eigen::Tensor<const unsigned short, 3, Eigen::RowMajor>>

input_tensor(tmp, Nz, Ny, Nx); // [Z][Y][X] in file

Eigen::TensorMap<Eigen::Tensor<unsigned short, 3, Eigen::RowMajor>>

output_tensor(ms, Nx, Ny, Nz); // [X][Y][Z] in memory

output_tensor = input_tensor.shuffle(Eigen::array<Eigen::Index, 3>{2, 1, 0});

FANS_free(tmp);

} else {

/* XYZ case: the slab is already in correct order */

FANS_free(ms); // dealloc mem

ms = tmp; // steal the buffer; no copy

}

/*--------------------------------------------------------------------

H5Sclose(memspace);

H5Sclose(filespace);

H5Dclose(dset_id);

H5Pclose(plist_id);

H5Fclose(file_id);

this->ComputeVolumeFractions();

{

if (ms) {

FANS_free(ms);

ms = nullptr;

}

{

std::snprintf(results_filename, sizeof(results_filename), "%s", output_fn);

hid_t plist_id = H5Pcreate(H5P_FILE_ACCESS);

H5Pset_fapl_mpio(plist_id, communicator, MPI_INFO_NULL);

results_file_id = H5Fcreate(results_filename, H5F_ACC_TRUNC, H5P_DEFAULT, plist_id);

H5Pclose(plist_id);

if (results_file_id < 0) {

throw std::runtime_error("Failed to create results file");

}

{

if (results_file_id >= 0) {

H5Fclose(results_file_id);

results_file_id = -1;

}

results_filename[0] = '\0';