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MUSIC/src/perturbation_theory.hh
2024-02-24 10:52:43 +01:00

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C++

// This file is part of MUSIC
// A software package to generate ICs for cosmological simulations
// Copyright (C) 2010-2024 by Oliver Hahn
//
// monofonIC is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// monofonIC 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 General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#pragma once
#include "mesh.hh"
#include "general.hh"
//! compute the jeans sound speed
/*! given a density in g/cm^-3 and a mass in g it gives back the sound
* speed in cm/s for which the input mass is equal to the jeans mass
* @param rho density
* @param mass mass scale
* @returns jeans sound speed
*/
inline double jeans_sound_speed( double rho, double mass )
{
const double G = 6.67e-8;
return pow( 6.0*mass/M_PI*sqrt(rho)*pow(G,1.5), 1.0/3.0 );
}
//! computes the density from the potential using the Laplacian
void compute_Lu_density( const grid_hierarchy& u, grid_hierarchy& fnew, unsigned order=4 );
//! computes the 2nd order density perturbations using also off-diagonal terms in the potential Hessian
void compute_LLA_density( const grid_hierarchy& u, grid_hierarchy& fnew, unsigned order=4 );
//! computes the source term for the 2nd order perturbations in the displacements
void compute_2LPT_source( const grid_hierarchy& u, grid_hierarchy& fnew, unsigned order=4 );
void compute_2LPT_source_FFT( config_file& cf_, const grid_hierarchy& u, grid_hierarchy& fnew );