Material for issue 494

CMakeLists.txt

cmake_minimum_required(VERSION 3.20...3.29)
project(example_spglib LANGUAGES C)

set(CMAKE_C_STANDARD 11)
set(CMAKE_C_STANDARD_REQUIRED ON)
set(CMAKE_C_EXTENSIONS OFF)

find_package(Spglib REQUIRED)

add_executable(example example.c)

target_link_libraries(example PRIVATE Spglib::symspg)

# Windows is weird like that :/
# https://stackoverflow.com/a/73550650
if (CMAKE_IMPORT_LIBRARY_SUFFIX)
    add_custom_command(TARGET example POST_BUILD
            COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_RUNTIME_DLLS:example> $<TARGET_FILE_DIR:example>
            COMMAND_EXPAND_LISTS
    )
endif ()

example.c

#include <stdio.h>
#include "spglib.h"

int main(int argc, char* argv[]) {

    double lattice[3][3] = {
        {7.255212,     0.000000,     0.000000},
        {3.627606,     6.283219,     0.000000},
        {0.000000,     0.000000,     5.712635},
    };
    double positions[8][3] = {
        {0.171633,     0.171632,     0.250000},
        {0.171633,     0.656735,     0.250000},
        {0.656734,     0.171632,     0.250000},
        {0.343266,     0.828368,     0.750000},
        {0.828367,     0.343265,     0.750000},
        {0.828367,     0.828368,     0.750000},
        {0.666699,     0.666601,     0.250000},
        {0.333301,     0.333399,     0.750000},
    };
    int types[8] = {11, 11, 11, 11, 11, 11, 12, 12};
    int num_atom = 8;
    double symprec = 1e-2;

	int num_primitive_atom = spg_standardize_cell(lattice, positions, types,
												  num_atom, 1, 0, symprec);

    printf("From C-API\n1.0\n");
    for(int i=0; i < 3; ++i)
    {
        printf("%lf %lf %lf\n", lattice[i][0], lattice[i][1], lattice[i][2]);
    }
    printf("  Na  Mg\n   6   2\nDirect\n");
    for(int i=0; i < num_primitive_atom; ++i)
    {
        printf("%lf %lf %lf\n", positions[i][0], positions[i][1], positions[i][2]);
    }
}

main.py

import spglib

if __name__ == '__main__':

    lattice = [[7.255212,     0.000000,     0.000000],
        [3.627606,     6.283219,     0.000000],
        [0.000000,     0.000000,     5.712635]]
    positions = [[0.171633,     0.171632,     0.250000],
        [0.171633,     0.656735,     0.250000],
        [0.656734,     0.171632,     0.250000],
        [0.343266,     0.828368,     0.750000],
        [0.828367,     0.343265,     0.750000],
        [0.828367,     0.828368,     0.750000],
        [0.666699,     0.666601,     0.250000],
        [0.333301,     0.333399,     0.750000]]
    numbers = [11, 11, 11, 11, 11, 11, 12, 12]
    cell = (lattice, positions, numbers)

    new_cell, new_frac_positions, new_numbers = spglib.standardize_cell(cell, to_primitive=True, symprec=1e-2)

    print("Lattice:")
    print(new_cell)
    print("\nPositions:")
    print(new_frac_positions)
    print("\nNumbers:")
    print(new_numbers)