Libcosm is a C library for calculating various physical quantities
(varisous distances, comoving volume, growth rate and etc.) in various
cosmological models including open- and flat-universe. Many papers
about cosmological issues (especially by observers!) adopt
Einstein-de-Sitter Universe, which has almost become obsolete due to
many observations done by observers themselves!! This is because there
is no simple analytic formula of various quatities (e.g. luminosity
and angular diameter distance) for cosmological models with
non-vanishing cosmological constant.  This library Libcosm privide a
set of useful routines for calculating follwing quantities under a
given cosmological model:

1. cosmological distance 
2. linear growth rate and critical over density
3. Press-Schechter mass function
4. linear power spectrum of density fluctuation

All files in this library is copyright 1999,2000 by Kohji Yoshikawa.
All rights reserved. Unpublished rights reserved under the copyright
laws of Japan. No warranty is available in using this
library. Redistribution and use in source and binary forms are
permitted provided that this entire copyright notice is duplicated in
all such copies, and that any documentation, announcements, and other
materials related to such distribution and use acknowledge that the
software was developed by Kohji Yoshikawa.

------------------------------------------------------------------------
*MANIFEST

Cosmology.c          : source code for Libcosm
Cosmology.h          : header file
Makefile             : makefile for compiling and building Libcosm
distance.c           : sample code
formation_rate.c     : sample code
growthrate.c         : sample code
massfunc.c           : sample code
power_spec.c         : sample code
sigma.c              : sample code
volume.c             : sample code


*The location of Libcosm library

  You can get the library from following addresses.

  FTP site  ftp://ftp.kusastro.kyoto-u.ac.jp/pub/kohji/libcosm
  WEB site  http://www.kusastro.kyoto-u.ac.jp/~kohji/research/libcosm

*Installation

  Libcosm is tested on following operating systems and compiles.

  True64 UNIX V4.0: DEC C and GCC v2.95.1
  LINUX 2.0.x and 2.2.x: GCC v.2.7.2.3 and GCC v.2.95.1
  Solaris v.2.5.1 and v.2.6: GCC v.2.95.1

  The procedures of intsalling Libcosm are as follows:

    1: Extracting the archive.
     % gunzip -cd libcosm.tar.gz | tar xvf -

    2: Compling and Building 
     % cd libcosm
     % make 

    3: Installing the library and the include file
     % cp Cosmology.h /usr/local/include
     % cp libcosm.a /usr/local/lib

    4: Testing (Compiling a sample code)
     % cc massfunc.c -o massfunc -I/usr/local/include -L/usr/local/lib -lcosm -lm
     % ./massfunc 

     This command produce the Press-Schecter mass function for standard 
     CDM Universe.

*API in Libcosm

The information for a cosmological models such as density parameter,
Hubble constant, and etc. is declared in the structure named
"Cosmology" in Cosmology.h. Users must declare at least one structure
of type "Cosmology" before using the APIs of Libcosm. Thus, the
beginning of typical code looks like follows. The function "init_cosm"
initialize various cosmological parameters for the structure.

-------------------------------------
#include "Cosmology.h"

int main(int argc, char **argv)
{
    Cosmology cosm;
    double omega0,omegab,lambda0,hubble,sigma8,pkindx;
    int  DM;
 
    omega0 = 1.e0;
    omegab = 0.01;
    lambda = 0.e0;
    hubble = 0.5;
    sigma8 = 0.5;
    pkindx = 1.e0;

    DM = 1; /* 1 for CDM and 2 for HDM with m=30eV */

    init_cosm(&cosm,omega0,omegab,lambda,hubble,pkindx,sigma8,DM);
          ......

-------------------------------------

Here, we describe the functions of available APIs.

>> double growthrate(Cosmology,double)

Returns the linear growthrate for a give cosmology. The returned
growthrate is normalized to unity at the present. The first argument 
is Cosmology structure and the second is the redshift.

>> double d_growthrate_dt(Cosmology,double) 

Returns the time derivative of linear growthrate in units of cgs unit
system. The nomalization of growthrate is the same as above function.
Two arguments are also the same as previous function.

>>double power_spec(Cosmology,double)

Retuens the present linear power spectrum of the density fluctuation.
The second argument is the wavenumber in units of [Mpc^(-1)].

>>double delta_c(Cosmology,double)

Retuens the critical overdensity for the spherical non-linear collapse
model. The second argument is the redshift.

>>double Delta_c(Cosmology,double)

Returns the mean overdensity of gravitationally objects collapsed at 
redshift z=zcol. The second argument is the redshift zcol.

>>double Transfer(Cosmology,double)

The transfer function of the density power spectrum for a give
cosmology. The second argumet is the wavenumber in units of [Mpc^(-1)].

>>double sigmaR(Cosmology,double)

Returns the present rms mass fluctuation on a scale R [Mpc]. The
second argument is the scale R in units of [Mpc].

>>double sigmaM(Cosmology,double)

Returns the present rms mass fluctuation on a mass scale M [Msolar]. The
second argument is the mass scale M in units of solar mass.

>>double psmassfunc(Cosmology,double,double)

Returns the Press--Schechter mass function in units of
[Mpc^(-3)Msolar^(-1)]. The second and third arguments are mass in
units of solar mass and the redshift, respectively.

>>double cumulative_psmassfunc(Cosmology,double,double)

Returns cumulative Press--Schechter mass function in units of [Mpc^(-3)].
The arguments are the same as the previous function.

>>double comoving_distance(Cosmology,double)

Returns the comoving distance to the redshift z. The unit of the
distance is [cm]. The second argument is the redshift z.

>>double angular_distance(Cosmology,double)

Returns the angular diameter distance in units of [cm]. The second
argument is the same as previous function.

>>double luminosity_distance(Cosmology,double)

Returns the luminosity distance in units of [cm] to the redshift
z. The second argument is the same as the previous function.

>>double dVoverdz(Cosmology,double)

Returns the differential comoving volume for unit solid angle in units
of [cm^3/redshift].  The second argument the redshift.

>>double comoving_volume(Cosmology,double,double)

Returns the comoving volume to the redshift z for unit solid angle.
The unit of the volume is [cm^3].