bh_qnmode.c

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/*
*  Copyright (C) 2007 Jolien Creighton
*
*  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 with program; see the file COPYING. If not, write to the
*  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
*  MA  02110-1301  USA
*/
 
/**
 * @defgroup lalsim_bh_qnmode lalsim-bh-qnmode
 * @ingroup lalsimulation_programs
 *
 * @brief Computes the quasi-normal modes of a black hole
 *
 * ### Synopsis
 *
 *     lalsim-bh-qnmode [-h] [-L] [-M Msolar] [-a a] -l l -m m -s s
 *
 * ### Description
 *
 * The `lalsim-bh-qnmode` utility prints the eigenvalues of a black hole
 * quasinormal mode with spin weight @p s (use -2 for gravitational quasinormal
 * modes) and mode numbers @p l and @p m for given black hole dimensionless
 * spin if the spin @p a is specified using the argument `-a`; or prints a
 * table of mode eigenvalues if @p a is not specified; or prints frequency and
 * quality factor if mass @p Msolar is specified.
 *
 * The utility uses Leaver's conventions (G = c = 2M = 1) if the option
 * `--leaver` is used
 *
 * ### Options
 *
 * <DL>
 * <DT>`-h`, `--help`</DT>
 * <DD>print a help message and exit</DD>
 * <DT>`-L, --leaver`</DT>
 * <DD>use Leaver's conventions: G = c = 2M = 1</DD>
 * <DT>`-M` Msolar</DT>
 * <DD>(optional) set black hole mass (solar masses)</DD>
 * <DT>`-a` a</DT>
 * <DD>(optional) set value of dimensionless spin parameter a/M, |a/M|<1 (Leaver: |a/M|<0.5)</DD>
 * <DT>`-l` l</DT>
 * <DD>(required) set value of mode number l, l>=0</DD>
 * <DT>`-m` m</DT>
 * <DD>(required) set value of mode number m, abs(m)<=l</DD>
 * <DT>`-s` s</DT>
 * <DD>(required) set value of spin weight s, s<=0</DD>
 * </DL>
 *
 * ### Environment
 *
 * The `LAL_DEBUG_LEVEL` can used to control the error and warning reporting of
 * `lalsim-bh-qnmode`.  Common values are: `LAL_DEBUG_LEVEL=0` which suppresses
 * error messages, `LAL_DEBUG_LEVEL=1`  which prints error messages alone,
 * `LAL_DEBUG_LEVEL=3` which prints both error messages and warning messages,
 * and `LAL_DEBUG_LEVEL=7` which additionally prints informational messages.
 *
 * ### Exit Status
 *
 * The `lalsim-bh-qnmode` utility exits 0 on success, and >0 if an error
 * occurs.
 *
 * ### Example
 *
 * The command:
 *
 *     lalsim-bh-qnmode -a 0.97 -M 10 -l 2 -m 2 -s -2
 *
 * outputs the freqeuency and quality factor for black hole ringdown
 * gravitational radiation in the l = m = 2 quasinormal mode for a
 * M = 10 solar mass hole with Kerr spin parameter a = 0.97 M.
 *
 * The command:
 *
 *     lalsim-bh-qnmode -L -l 2 -m 0 -s -2
 *
 * prints a table of Kerr quasinormal frequencies and angular separation
 * constants for the fundamental mode corresponding to l = 2 and m = 1
 * for gravitational perturbations (s = -2) in Leaver's conventions:
 *
@verbatim
# quasinormal mode table for l=2 m=0 s=-2 (Leaver's conventions)
#  a            A                       omega
0.0000  (4.00000,+0.00000)      (+0.747343,-0.177925)
0.1000  (3.99722,+0.00139)      (+0.750248,-0.177401)
0.2000  (3.98856,+0.00560)      (+0.759363,-0.175653)
0.3000  (3.97297,+0.01262)      (+0.776108,-0.171989)
0.4000  (3.94800,+0.02226)      (+0.803835,-0.164313)
0.4500  (3.93038,+0.02763)      (+0.824009,-0.156965)
0.4900  (3.91269,+0.03152)      (+0.844509,-0.147065)
0.4999  (3.90770,+0.03227)      (+0.850231,-0.143650)
 
0.0000  (4.00000,-0.00000)      (-0.747343,-0.177925)
0.1000  (3.99722,-0.00139)      (-0.750248,-0.177401)
0.2000  (3.98856,-0.00560)      (-0.759363,-0.175653)
0.3000  (3.97297,-0.01262)      (-0.776108,-0.171989)
0.4000  (3.94800,-0.02226)      (-0.803835,-0.164313)
0.4500  (3.93038,-0.02763)      (-0.824009,-0.156965)
0.4900  (3.91269,-0.03152)      (-0.844509,-0.147065)
0.4999  (3.90770,-0.03227)      (-0.850231,-0.143650)
@endverbatim
 *
 * Compare with Table 3 of E. W. Leaver, "An analytic representation of
 * quasi-normal modes of Kerr black holes", Proc. R. Soc. Lond. A @b 402 285
 * (1985).
 */
 
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
 
#include <lal/LALStdlib.h>
#include <lal/LALgetopt.h>
#include <lal/LALConstants.h>
#include <lal/LALSimBlackHoleRingdown.h>
 
#define a_invalid -100.0 /* invalid */
#define l_invalid (INT_MIN + 1) /* invalid */
#define m_invalid (INT_MAX) /* invalid */
#define s_invalid (INT_MAX) /* invalid */
REAL8 M = 0.0;
REAL8 a = a_invalid;
int l = l_invalid;
int m = m_invalid;
int s = s_invalid;
int leaver = 0;
 
int usage(const char *program);
int parseargs(int argc, char **argv);
int output_mode_table(void);
int output_mode(void);
 
 
int output_mode_table(void)
{
        double avec[] = {0.0,0.1,0.2,0.3,0.4,0.45,0.49,0.4999};
        int asign;
        size_t numa = XLAL_NUM_ELEM(avec);
        size_t i;
 
        fprintf(stdout, "# quasinormal mode table for l=%d m=%d s=%d ", l, m, s);
        if (leaver)
                fprintf(stdout, "(Leaver's conventions)\n");
        else
                fprintf(stdout, "(standard conventions)\n");
        if (M == 0.0)
                fprintf(stdout, "#  a   \t        %s        \t        omega\n", leaver ? "A" : "E");
        else
                fprintf(stdout, "#  a   \t  frequency (Hz)  \t   quality   \n");
 
        /* do positive spins first, then do negative spins */
        for (asign = 1; abs(asign) == 1; asign -= 2) {
                for (i = 0; i < numa; ++i) {
                        COMPLEX16 A, omega;
                        a = avec[i];
                        XLALSimBlackHoleRingdownModeEigenvaluesLeaver(&A, &omega, asign*a, l, m, s);
                        if (!leaver) { /* convert to standard conventions */
                                a *= 2.0;
                                omega *= 0.5;
                                A += s*(s+1);
                        }
                        if (M == 0.0)
                                fprintf(stdout, "%.4f \t(%.5f,%+.5f)\t(%+.6f,%.6f)\n", a, creal(A), cimag(A), creal(omega), cimag(omega));
                        else {
                                double f, Q;
                                f = fabs(creal(omega) / (LAL_TWOPI * M * LAL_MTSUN_SI));
                                Q = fabs(creal(omega)) / (-2.0 * cimag(omega));
                                fprintf(stdout, "%.4f \t %12.3f \t\t %8.3f\n", a, f, Q);
                        }
                }
                if (asign == 1)
                        fprintf(stdout, "\n");
        }
        return 0;
}
 
int output_mode(void)
{
        COMPLEX16 A, omega;
 
        if (!leaver) /* spin was not specified in Leaver conventions */
                a *= 0.5; /* change to Leaver conventions */
 
        XLALSimBlackHoleRingdownModeEigenvaluesLeaver(&A, &omega, a, l, m, s);
 
        if (!leaver) { /* change from Leaver conventions */
                omega *= 0.5;
                a *= 2.0;
        }
 
        /*
         * if mass has been specified, return f and Q
         * otherwise return omega in either leaver or standard conventions
         */
 
        fprintf(stdout, "using %s conventions\n", leaver ? "Leaver's" : "standard");
        fprintf(stdout, "mode l = %d, m = %d, s = %d\n", l, m, s);
        fprintf(stdout, "spin a = %g (dimensionless)\n", a);
        fprintf(stdout, "M * omega = (%+.6f,%+.6f)\n", creal(omega), cimag(omega));
        if (M != 0.0) {
                double f, Q;
                f = fabs(creal(omega) / (LAL_TWOPI * M * LAL_MTSUN_SI));
                Q = fabs(creal(omega)) / (-2.0 * cimag(omega));
 
                fprintf(stdout, "mass M = %g solar masses\n", M);
                fprintf(stdout, "frequency f = %g Hz\n", f);
                fprintf(stdout, "quality Q = %g\n", Q);
        }
 
        return 0;
}
 
 
int main(int argc, char *argv[])
{
        XLALSetErrorHandler(XLALBacktraceErrorHandler);
 
        parseargs(argc, argv);
 
        if (a == a_invalid)
                output_mode_table();
        else
                output_mode();
 
        LALCheckMemoryLeaks();
        return 0;
}
 
int parseargs( int argc, char **argv )
{
        struct LALoption long_options[] = {
                        { "help", no_argument, 0, 'h' },
                        { "leaver", no_argument, 0, 'L' },
                        { "mass", required_argument, 0, 'M' },
                        { "spin", required_argument, 0, 'a' },
                        { "l", required_argument, 0, 'l' },
                        { "m", required_argument, 0, 'm' },
                        { "s", required_argument, 0, 's' },
                        { 0, 0, 0, 0 }
                };
        char args[] = "hLM:a:l:m:s:";
        while (1) {
                int option_index = 0;
                int c;
 
                c = LALgetopt_long_only(argc, argv, args, long_options, &option_index);
                if (c == -1) /* end of options */
                        break;
 
                switch (c) {
                        case 0: /* if option set a flag, nothing else to do */
                        if (long_options[option_index].flag)
                                break;
                        else {
                                fprintf(stderr, "error parsing option %s with argument %s\n", long_options[option_index].name, LALoptarg);
                                exit(1);
                        }
                case 'h': /* help */
                        usage(argv[0]);
                        exit(0);
                case 'L': /* leaver */
                        leaver = 1;
                        break;
                case 'M': /* mass */
                        M = atof(LALoptarg);
                        break;
                case 'a': /* spin */
                        a = atof(LALoptarg);
                        break;
                case 'l':
                        l = atoi(LALoptarg);
                        break;
                case 'm':
                        m = atoi(LALoptarg);
                        break;
                case 's':
                        s = atoi(LALoptarg);
                        break;
                case '?':
                default:
                        fprintf(stderr, "unknown error while parsing options\n");
                        exit(1);
                }
        }
 
        if (LALoptind < argc) {
                fprintf(stderr, "extraneous command line arguments:\n");
                while (LALoptind < argc)
                        fprintf(stderr, "%s\n", argv[LALoptind++]);
                exit(1);
        }
 
        if (l == l_invalid || m == m_invalid || s == s_invalid) {
                fprintf(stderr, "must specify l, m, and s\n");
                usage(argv[0]);
                exit(1);
        }
 
        if (!(a == a_invalid || (leaver && fabs(a) < 0.5) || (!leaver && fabs(a) < 1.0))) {
                fprintf(stderr, "must specify |a| < 1 (or |a| < 0.5 with Leaver's conventions)\n");
                exit(1);
        }
 
        if (leaver && M != 0.0) {
                fprintf(stderr, "do not use both --leaver and --mass options\n");
                usage(argv[0]);
                exit(1);
        }
 
        return 0;
}
 
int usage(const char *program)
{
        fprintf(stderr, "usage: %s [options]\n", program);
        fprintf(stderr, "options:\n");
        fprintf(stderr, "\t-h, --help     \tprint this message and exit\n");
        fprintf(stderr, "\t-L, --leaver   \tuse Leaver's conventions\n");
        fprintf(stderr, "\t-M Msolar      \t(optional) set black hole mass (solar masses)\n");
        fprintf(stderr, "\t-a a           \t(optional) set value of a, |a|<1 (Leaver: |a|<0.5)\n");
        fprintf(stderr, "\t-l l           \t(required) set value of l, l>=0\n");
        fprintf(stderr, "\t-m m           \t(required) set value of m, abs(m)<=l\n");
        fprintf(stderr, "\t-s s           \t(required) set value of s, s<=0\n");
        fprintf(stderr, "description:\n");
        fprintf(stderr, "\tprints the eigenvalues for given a if a is specified\n");
        fprintf(stderr, "\tprints a table of mode eigenvalues if a is not specified\n");
        fprintf(stderr, "\tprints frequency and quality factor if mass is specified\n");
        fprintf(stderr, "\tuses Leaver's conventions (G = c = 2M = 1) if --leaver is used\n");
        return 0;
}