libcosmo and cosmic
===================

The library implements a C++ class that defines the basic cosmological
parameters H_o, Omega_m, and Omega_Lambda. Omega_k is defined such
that the Omegas satisfy the Friedmann Equation, that is, the sum of
the density parameters for matter, Lambda, and curvature is equal to 1.
An instantiation of the class also has a redshift, from which the standard
distance measures are calculated.  An angular scale (kpc/arcsec) is
also calculated.

The accompanying program ("cosmic") provides an example use of this
class, although "cosmic" is also useful on its own.  It prompts the
user for H_o, Omega_m, and Omega_Lambda.  It then asks for a redshift
and prints the resulting calculations to the screen, then repeats until
stopped.  Cosmic also has a batch mode useful for calculating distances
and angular scales for a large number of redshifts.  It takes a file as
input with one redshift per line and outputs the results to cosmic.out
or to a user specified file.  A complete list of command line options
for cosmic is included in this README file.

Installation
============

A Makefile is included with the distribution. The following options are
available in the Makefile:

	make libcosmo  - compile the library only
	make cosmic    - compile the "cosmic" program only
	make all       - compile both the library and "cosmic"
	make clean     - remove intermediate files
	make distclean - remove all compiled files

Class Library Interface
=======================

The public interface of the class Cosmo is as follows:

Cosmo()
	default constructor.  H_o = 67.04, O_m = 0.3183, O_L = 0.6817

Cosmo(const double h, const double om, const double ol)
	constructor that allows the cosmological parameters to be set explicitly

Cosmo(cont Cosmo& c)
	copy constructor

overloaded operators
--------------------
Cosmo& operator=(const Cosmo& c)
	assignment operator

member functions
----------------
double
z()
	returns the redshift

double
dL()
	returns the luminosity distance

double
dA()
	returns the angular diameter distance

double
dC()
	returns the line-of-sight comoving distance

double
dM()
	returns the transverse comoving distance

double
VC()
	returns the comoving volume out to the redshift of the object

double
scale()
	returns the number of kpc per arcsec at the redshift of the object

double
rhoCrit()
	returns the critical density at the redshift of the object

double
lookback()
	returns the lookback time to the redshift of the object

double
age()
	returns the age of the universe at z=0 in the given cosmology

void
printLong()
	prints all of the above plus the cosmological parameters, formatted

void
printShort(ostream& os = cout)
	prints distances and scales on a single line to the specified stream.
	stream defaults to cout.

void
printShortHeader(ostream& os = cout)
	prints a header for use with printShort() to the specified stream.
	stream defaults to cout.

void
printParams(ostream& os = cout, const char* leader = "")
	prints the current cosmological parameters to the specified stream with
	the text in "leader" at the beginning of the line.
	stream defaults to cout.

void
setCosmology(const double h, const double om, const double ol)
	sets the cosmological parameters. sets the derived quantities as
	well if the object's redshift has already been set.

void
setRedshift(const double z)
	sets the redshift of the object and the derived quantities

void
getCosmologyFromUser()
	prompt the user for the cosmological parameters

non-member functions
--------------------
double
promptForParam(const char* description, const DP defaultVal)
	generic function to get a number from the user, using a
	default value if the user does not provide a response.

Example
-------

#include "cosmo.h"

int main(int argc, char** argv)
{
   Cosmo *c = new Cosmo(70, 1.0, 0.0);  // Einstein - de Sitter universe
   double z = 0.1;

   // print distances from z=0.1 to 1 in steps of 0.1
   while (z <= 1.0) {
      c->setRedshift(z);  // set z
      c->printLong();  // print the derived quantities
      z += 0.1;
   }
   return 0;
}

User interface to cosmic
========================

Cosmic supports a number of command line options, invoked as option=value:

option  type     default    description
----------------------------------------------------------------------------
h       float    67.04      Value of the Hubble constant

m       float    0.3183     Value of Omega matter

l       float    0.6817     Value of Omega Lambda

z       float    --         Single redshift for quick mode; calculates
                            values for the given redshift, prints the
                            results, then exits.

batch   string   --         Input file of redshifts for batch mode
                            processing; one redshift per line

outfile string   cosmic.out Output file for batch mode results

prompt  boolean  yes        Prompt the user for the cosmological
                            parameters

quiet   boolean  no         Suppress the copyright message

html    boolean  no         Format the output using HTML

help    boolean  no         Print a help message

version boolean  no         Print the version number of cosmic

Each of the boolean options may be turned on by prepending a "-" to the
option name. Similarly, they may be turned off by prepending "-no" to
the option name.  For example, "-help" is equivalent to "help=yes" and
"-noprompt" is equivalent to "prompt=no".

History
=======

Cosmic:
05 Feb 2003  1.0    Initial version
10 Feb 2003  1.01   Improved handling of non-numeric redshifts
03 Mar 2003  1.02   Added batch mode to print a list of distances given
                    an input file with a list of redshifts.  Added help
                    message and improved handling of command-line
                    arguments.
06 Mar 2003  1.03   Improved handling of user input
10 Jul 2003  1.04   Added additional command line options:
                    * Set individual cosmological parameters on command line
                    * Set output file name for batch mode
                    * Suppress prompting for cosmological parameters
15 Jul 2003  2.0    Adapted to work with libcosmo version 2.0
15 Apr 2004  2.0.1  Improved handling of improper user input
15 Mar 2005  2.0.2  Cleaned up to compile under g++ with fewer warnings
31 Mar 2006  2.0.3  Bug fixes:
                    * Added include statement for <cmath> to cosmic.cc
                      to allow compiling under gcc 4 on OS X.
                    * Changed Makefile to fix dependencies on libcosmo.a
                      so that it wouldn't force a re-compile even when
                      everything was up to date.
02 Aug 2006  2.0.4  Added "quick mode" option for providing a redshift
                    on the command line.  Further improved handling of
                    invalid user input.
04 Aug 2006  2.0.5  Multiple changes:
                    * Moved validation of numeric user input into libcosmo
                      since it was also useful within the class's member
                      functions.
                    * Eliminated command line option for curvature since
                      libcosmo no longer supports it as a user-definable
                      parameter.
01 Jul 2007  2.0.6  Cleaned up header includes.
27 Nov 2007  2.0.7  Improved handling of user-input redshifts, including
                    allowing for a redshift of 0.
22 Nov 2011  2.0.8  Updated header includes for compatibility with newer
                    versions of gcc.
12 Jul 2021  2.1.0  Added HTML output option.

libcosmo:
05 Feb 2003  1.0    Initial version
11 Feb 2003  1.01   Added inspection function for redshift, changed
                    default parameters to those from the initial WMAP
                    results.
25 Feb 2003  1.02   Fixed bug in initialization of z_
25 Feb 2003  1.03   Added functions for more compact output and for output
                    to files.
06 Mar 2003  1.04   Added function to get cosmological parameters from the
                    user interactively.
05 Jun 2003  1.05   Internal clean-up of output functions to reduce
                    code duplication and improve versatility
18 Jun 2003  1.06   Initialization bug in getCosmologyFromUser() fixed
15 Jul 2003  2.0    Numerous changes including:
                    * All distance measures now based on line-of-sight
                      comoving distance
                    * Universe with non-zero Lambda now uses Romberg
                      integration to calculate distances
                    * Added option for non-zero contribution to Omega from
                      curvature.
                    * Added calculation of transverse co-moving distance
                    * Added calculation of comoving volume out to redshift z
                    * Added calculation of lookback time and age of the
                      Universe
                    * Rationalized public interface to output functions
16 Jul 2003  2.0.1  Improved handling of non-numeric values input by user
                    in getCosmologyFromUser()
15 Apr 2004  2.0.2  Minor fix to allow compilation with certain strict
                    compilers
15 Mar 2005  2.0.3  Cleaned up to compile under g++ with fewer warnings;
                    added calculation of critical density at z
05 Jan 2006  2.0.4  Simplified code in output functions and fixed
                    formatting of printParams output if called multiple
                    times.
04 Aug 2006  2.1    Multiple changes:
                    * Added non-member function for validation of numeric
                      user input. The function is adapted from the one that
                      was included in cosmic v2.0.4.
                    * Fixed minor bug in calculation of comoving volume in
                      universes with curved geometry.
                    * Eliminated Omega curvature as a user-definable
                      parameter in order to ensure that the Friedmann
                      Equation is always satisfied.
                    * Changed output to print q_0 regardless of the value
                      of Omega Lambda.
01 Jul 2007  2.1.1  Fixed possible segfault in Cosmo::romberg and cleaned
                    up header includes. Thanks to Patrick Hudelot for finding
                    the bug in the Romberg integration code.
27 Nov 2007  2.1.2  Multiple changes:
                    * Fixed bug that was causing comoving volume to be
                      calculated incorrectly for universes with flat
                      geometry. Thanks to Steven Bamford of the University
                      of Portsmouth for finding this bug.
                    * Improved the intialization function and the printLong()
                      functions to better handle z=0.
22 Nov 2011  2.1.3  Multiple changes:
                    * Fixed a bug in calculating the comoving volume for Omega-
                      kappa != 0. Thanks to Dimitrios Emmanoulopoulos for
                      finding this bug.
                    * Fixed a bug in the constructor that prevented Omega-kappa
                      from being set to a value < 0.
                    * Updated header includes for compatibility with newer
                      versions of gcc.
23 Nov 2013  2.1.4  Multiple changes:
                    * Redefined the integrand for computing the age of the
                      Universe using variable substitution so it successfully
                      integrates from z=0 to z=infinity.
                    * Changed the default values of the cosmological parameters
                      to those from Planck + WMAP polarization at low
                      multipoles, Table 2 of Planck Collaboration, "Planck 2013
                      results. XVI. Cosmological parameters," Astronomy &
                      Astrophyics submitted, 2013.
                    * Added the lookback time to z to the output in batch mode.
12 Jul 2021  2.1.5  Added HTML output option.

Copyright
=========

Copyright (C) 2003-2021  Joshua Kempner <josh@kempner.net>
This program 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 2 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 General Public License along
with this program; if not, write to the Free Software Foundation, Inc., 59
Temple Place - Suite 330, Boston, MA 02111-1307, USA.

Please send any bug fixes, enhancements, or useful comments by email to
josh@kempner.net.