diff --git a/examples/CosmologicalBox/cosmo.yml b/examples/CosmologicalBox/cosmo.yml
new file mode 100644
index 0000000000000000000000000000000000000000..b0fbfaf3fa696d9dd3531369e1811c22cc1f4af4
--- /dev/null
+++ b/examples/CosmologicalBox/cosmo.yml
@@ -0,0 +1,50 @@
+# Define the system of units to use internally.
+InternalUnitSystem:
+ UnitMass_in_cgs: 1.989e43 # 10^10 M_sun in grams
+ UnitLength_in_cgs: 3.085678e24 # Mpc in centimeters
+ UnitVelocity_in_cgs: 1e0 # km/s in centimeters per second
+ UnitCurrent_in_cgs: 1 # Amperes
+ UnitTemp_in_cgs: 1 # Kelvin
+
+# UnitMass_in_cgs: 1 # Grams
+# UnitLength_in_cgs: 1 # Centimeters
+# UnitVelocity_in_cgs: 1 # Centimeters per second
+# UnitCurrent_in_cgs: 1 # Amperes
+# UnitTemp_in_cgs: 1 # Kelvin
+
+# Parameters governing the time integration
+TimeIntegration:
+ time_begin: 0. # The starting time of the simulation (in internal units).
+ time_end: 1. # The end time of the simulation (in internal units).
+ dt_min: 1e-6 # The minimal time-step size of the simulation (in internal units).
+ dt_max: 1e-2 # The maximal time-step size of the simulation (in internal units).
+
+# Parameters governing the snapshots
+Snapshots:
+ basename: uniformBox # Common part of the name of output files
+ time_first: 0. # Time of the first output (in internal units)
+ delta_time: 0.01 # Time difference between consecutive outputs (in internal units)
+
+# Parameters governing the conserved quantities statistics
+Statistics:
+ delta_time: 1e-2 # Time between statistics output
+
+# Parameters for the hydrodynamics scheme
+SPH:
+ resolution_eta: 1.2348 # Target smoothing length in units of the mean inter-particle separation (1.2348 == 48Ngbs with the cubic spline kernel).
+ CFL_condition: 0.1 # Courant-Friedrich-Levy condition for time integration.
+
+# Parameters related to the initial conditions
+InitialConditions:
+ file_name: ./uniformBox.hdf5 # The file to read
+
+Cosmology:
+ Omega_m: 0.307
+ Omega_r: 0.000
+ Omega_lambda: 0.693
+ Omega_b: 0.0455
+ h: 0.6777
+ a_begin: 0.0078125
+ a_end: 1.0
+
+
diff --git a/examples/CosmologicalBox/makeIC.py b/examples/CosmologicalBox/makeIC.py
new file mode 100644
index 0000000000000000000000000000000000000000..01e37c67b6e2eec2984d62f4ffd503b23b5bd9ec
--- /dev/null
+++ b/examples/CosmologicalBox/makeIC.py
@@ -0,0 +1,109 @@
+###############################################################################
+ # This file is part of SWIFT.
+ # Copyright (c) 2013 Pedro Gonnet (pedro.gonnet@durham.ac.uk),
+ # Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ #
+ # This program is free software: you can redistribute it and/or modify
+ # it under the terms of the GNU Lesser General Public License as published
+ # by the Free Software Foundation, either version 3 of the License, or
+ # (at your option) any later version.
+ #
+ # This program is distributed in the hope that it will be useful,
+ # but WITHOUT ANY WARRANTY; without even the implied warranty of
+ # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ # GNU General Public License for more details.
+ #
+ # You should have received a copy of the GNU Lesser General Public License
+ # along with this program. If not, see <http://www.gnu.org/licenses/>.
+ #
+ ##############################################################################
+
+import h5py
+import sys
+from numpy import *
+
+# Generates a swift IC file containing a cartesian distribution of particles
+# at a constant density and pressure in a cubic box
+
+# Parameters
+periodic= 1 # 1 For periodic box
+boxSize = 1.
+L = int(sys.argv[1]) # Number of particles along one axis
+rho = 2. # Density
+P = 1. # Pressure
+gamma = 5./3. # Gas adiabatic index
+eta = 1.2349 # 48 ngbs with cubic spline kernel
+fileName = "uniformBox.hdf5"
+
+#---------------------------------------------------
+numPart = L**3
+mass = boxSize**3 * rho / numPart
+internalEnergy = P / ((gamma - 1.)*rho)
+
+#--------------------------------------------------
+
+#File
+file = h5py.File(fileName, 'w')
+
+# Header
+grp = file.create_group("/Header")
+grp.attrs["BoxSize"] = boxSize
+grp.attrs["NumPart_Total"] = [numPart, 0, 0, 0, 0, 0]
+grp.attrs["NumPart_Total_HighWord"] = [0, 0, 0, 0, 0, 0]
+grp.attrs["NumPart_ThisFile"] = [numPart, 0, 0, 0, 0, 0]
+grp.attrs["Time"] = 0.0
+grp.attrs["NumFilesPerSnapshot"] = 1
+grp.attrs["MassTable"] = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
+grp.attrs["Flag_Entropy_ICs"] = 0
+grp.attrs["Dimension"] = 3
+
+#Runtime parameters
+grp = file.create_group("/RuntimePars")
+grp.attrs["PeriodicBoundariesOn"] = periodic
+
+#Units
+grp = file.create_group("/Units")
+grp.attrs["Unit length in cgs (U_L)"] = 1.
+grp.attrs["Unit mass in cgs (U_M)"] = 1.
+grp.attrs["Unit time in cgs (U_t)"] = 1.
+grp.attrs["Unit current in cgs (U_I)"] = 1.
+grp.attrs["Unit temperature in cgs (U_T)"] = 1.
+
+#Particle group
+grp = file.create_group("/PartType0")
+
+v = zeros((numPart, 3))
+ds = grp.create_dataset('Velocities', (numPart, 3), 'f')
+ds[()] = v
+v = zeros(1)
+
+m = full((numPart, 1), mass)
+ds = grp.create_dataset('Masses', (numPart,1), 'f')
+ds[()] = m
+m = zeros(1)
+
+h = full((numPart, 1), eta * boxSize / L)
+ds = grp.create_dataset('SmoothingLength', (numPart,1), 'f')
+ds[()] = h
+h = zeros(1)
+
+u = full((numPart, 1), internalEnergy)
+ds = grp.create_dataset('InternalEnergy', (numPart,1), 'f')
+ds[()] = u
+u = zeros(1)
+
+
+ids = linspace(0, numPart, numPart, endpoint=False).reshape((numPart,1))
+ds = grp.create_dataset('ParticleIDs', (numPart, 1), 'L')
+ds[()] = ids + 1
+x = ids % L;
+y = ((ids - x) / L) % L;
+z = (ids - x - L * y) / L**2;
+coords = zeros((numPart, 3))
+coords[:,0] = z[:,0] * boxSize / L + boxSize / (2*L)
+coords[:,1] = y[:,0] * boxSize / L + boxSize / (2*L)
+coords[:,2] = x[:,0] * boxSize / L + boxSize / (2*L)
+ds = grp.create_dataset('Coordinates', (numPart, 3), 'd')
+ds[()] = coords
+
+file.close()
diff --git a/examples/main.c b/examples/main.c
index 6cd5f9fa6eb9b48fef4c040f6b3a90b909fd0d3b..a69ee02096eacc8952b4520d5df3b570ba623f57 100644
--- a/examples/main.c
+++ b/examples/main.c
@@ -472,6 +472,11 @@ int main(int argc, char *argv[]) {
phys_const_print(&prog_const);
}
+ /* Initialise the cosmology */
+ struct cosmology cosmo;
+ if(with_cosmology) cosmology_init(params, &us, &prog_const, &cosmo);
+ if(with_cosmology) cosmology_print(&cosmo);
+
/* Initialise the hydro properties */
struct hydro_props hydro_properties;
if (with_hydro) hydro_props_init(&hydro_properties, params);
diff --git a/src/Makefile.am b/src/Makefile.am
index 690c5a0589e7cbd71ec40c2dd2bcdd53d848bd4b..6978f1c5b186a70e019072821f503e4451a35012 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -47,7 +47,7 @@ include_HEADERS = space.h runner.h queue.h task.h lock.h cell.h part.h const.h \
sourceterms_struct.h statistics.h memswap.h cache.h runner_doiact_vec.h profiler.h \
dump.h logger.h active.h timeline.h xmf.h gravity_properties.h gravity_derivatives.h \
gravity_softened_derivatives.h vector_power.h collectgroup.h hydro_space.h sort_part.h \
- chemistry.h chemistry_io.h chemistry_struct.h
+ chemistry.h chemistry_io.h chemistry_struct.h cosmology.h
# Common source files
AM_SOURCES = space.c runner.c queue.c task.c cell.c engine.c \
@@ -59,7 +59,7 @@ AM_SOURCES = space.c runner.c queue.c task.c cell.c engine.c \
statistics.c runner_doiact_vec.c profiler.c dump.c logger.c \
part_type.c xmf.c gravity_properties.c gravity.c \
collectgroup.c hydro_space.c equation_of_state.c \
- chemistry.c
+ chemistry.c cosmology.c
# Include files for distribution, not installation.
diff --git a/src/cosmology.c b/src/cosmology.c
new file mode 100644
index 0000000000000000000000000000000000000000..2eb83a5c428a76239bcf3c91f4bff2312a5e32af
--- /dev/null
+++ b/src/cosmology.c
@@ -0,0 +1,106 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2017 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+
+/**
+ * @file cosmology.c
+ * @brief Functions relating cosmological parameters
+ */
+
+/* This object's header. */
+#include "cosmology.h"
+
+/* Some standard headers */
+#include <math.h>
+
+/**
+ * @brief Update the cosmological parameters to the current simulation time.
+ *
+ * @param c The #cosmology struct.
+ * @param e The #engine containing information about the simulation time.
+ */
+void cosmology_update(struct cosmology *c, const struct engine *e) {
+
+ /* Get scale factor */
+ const double a = c->a_begin * exp(e->ti_current * e->timeBase);
+ const double a_inv = 1. / a;
+ c->a = a;
+ c->a_inv = a_inv;
+
+ /* Redshift */
+ c->z = a_inv - 1.;
+
+ /* E(z) */
+ const double Omega_r = c->Omega_r;
+ const double Omega_m = c->Omega_m;
+ const double Omega_l = c->Omega_lambda;
+ const double Omega_k = c->Omega_k;
+
+ const double E_z2 = Omega_r * a_inv * a_inv * a_inv * a_inv
+ + Omega_m * a_inv * a_inv * a_inv
+ + Omega_k * a_inv * a_inv
+ + Omega_l;
+
+ const double E_z = sqrt(E_z2);
+
+ /* H(z) */
+ c->H = c->H0 * E_z;
+}
+
+
+void cosmology_init(const struct swift_params* params,
+ const struct unit_system* us,
+ const struct phys_const* phys_const,
+ struct cosmology *c) {
+
+ /* Read in the cosmological parameters */
+ c->Omega_m = parser_get_param_double(params, "Cosmology:Omega_m");
+ c->Omega_r = parser_get_param_double(params, "Cosmology:Omega_r");
+ c->Omega_lambda = parser_get_param_double(params, "Cosmology:Omega_lambda");
+ c->Omega_b = parser_get_param_double(params, "Cosmology:Omega_b");
+ c->h = parser_get_param_double(params, "Cosmology:h");
+ c->a_begin = parser_get_param_double(params, "Cosmology:a_begin");
+ c->a_end = parser_get_param_double(params, "Cosmology:a_end");
+
+ /* Construct derived quantities */
+ c->Omega_k = 1. - (c->Omega_m + c->Omega_r + c->Omega_lambda);
+ const double km = 1.e5 / units_cgs_conversion_factor(us, UNIT_CONV_LENGTH);
+ const double s = 1. / units_cgs_conversion_factor(us, UNIT_CONV_TIME);
+ message("km=%e", km);
+ const double H0_cgs = 100. * c->h * km / s / (1.e6 * phys_const->const_parsec); /* s^-1 */
+ message("s=%e", s);
+ c->H0 = H0_cgs;
+
+ /* Set remaining variables to invalid values */
+ c->H = -1.;
+ c->a = -1.;
+ c->a_inv = -1;
+ c->z = -1.;
+}
+
+
+void cosmology_print(const struct cosmology *c) {
+
+ message("Density parameters: [O_m, O_l, O_b, O_k, O_r] = [%f, %f, %f, %f, %f]",
+ c->Omega_m, c->Omega_lambda, c->Omega_b, c->Omega_k, c->Omega_r);
+ message("Hubble constant: h = %f, H_0 = %e U_t^(-1) (internal units)",
+ c->h, c->H0);
+
+}
+
+
diff --git a/src/cosmology.h b/src/cosmology.h
new file mode 100644
index 0000000000000000000000000000000000000000..7ee19ced7fd575b6eacf9a1a63c2f6bf7db6684a
--- /dev/null
+++ b/src/cosmology.h
@@ -0,0 +1,84 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2017 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_COSMOLOGY_H
+#define SWIFT_COSMOLOGY_H
+
+/* Config parameters. */
+#include "../config.h"
+
+#include "engine.h"
+#include "parser.h"
+
+/**
+ * @brief Cosmological parameters
+ */
+struct cosmology{
+
+ /*! Current expansion factor of the Universe */
+ double a;
+
+ /*! Inverse of the current expansion factor of the Universe */
+ double a_inv;
+
+ /*! Current redshift */
+ double z;
+
+ /*! Hubble constant at the current redshift (in internal units) */
+ double H;
+
+ /*! Starting expansion factor */
+ double a_begin;
+
+ /*! Ending expansion factor */
+ double a_end;
+
+ /*! Reduced Hubble constant (H0 / (100km/s/Mpc)) */
+ double h;
+
+ /*! Hubble constant at z = 0 (in internal units) */
+ double H0;
+
+ /*! Matter density parameter */
+ double Omega_m;
+
+ /*! Baryon density parameter */
+ double Omega_b;
+
+ /*! Radiation constant density parameter */
+ double Omega_lambda;
+
+ /*! Cosmological constant density parameter */
+ double Omega_r;
+
+ /*! Curvature density parameter */
+ double Omega_k;
+};
+
+void cosmology_update(struct cosmology *c, const struct engine *e);
+
+void cosmology_init(const struct swift_params* params,
+ const struct unit_system* us,
+ const struct phys_const* phys_const,
+ struct cosmology *c);
+
+void cosmology_print(const struct cosmology *c);
+
+
+#endif /* SWIFT_COSMOLOGY_H */
+
diff --git a/src/swift.h b/src/swift.h
index eda566b19697ceeb1d66b266b44f4769be227585..ed7260ff4303154249339e84b8a501e52e08e60f 100644
--- a/src/swift.h
+++ b/src/swift.h
@@ -31,6 +31,7 @@
#include "clocks.h"
#include "const.h"
#include "cooling.h"
+#include "cosmology.h"
#include "cycle.h"
#include "debug.h"
#include "dump.h"