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include <math.h>
include "starlist.h"
# ST_ESMIX -- Compute the percentage of elliptical galaxies.
procedure st_esmix (egal, nstar, esmix, seed)
int egal[ARB] # array of types
int nstar # number of objects
real esmix # fraction of elliptical galaxies
long seed # seed for random number generator
int i
real fraction
real urand()
begin
do i = 1, nstar {
fraction = urand (seed)
if (fraction <= esmix)
egal[i] = ST_DEVAUC
else
egal[i] = ST_EXP
}
end
# ST_ROUND -- Compute an array of roundness parameters.
# For ellipical models use a uniform distribution of axial ratios.
# For spiral models use a uniform inclination distribution. Compute
# the axial ratio with a .1 flatness parameter from Holmberg (Stars
# and Stellar Systems). Then add cosecant absorption factor to the
# the magnitudes with a limit of 10 in the cosecant.
procedure st_round (egal, mag, round, nstars, ar, alpha, seed)
int egal[ARB] # array of galaxy types
real mag[ARB] # magnitudes
real round[ARB] # array of roundness values
int nstars # number of stars
real ar # minimum roundness value
real alpha # absorption coefficent
long seed # seed for the random number generator
int i
real dr, s, urand()
begin
dr = (1. - ar)
do i = 1, nstars {
if (egal[i] == ST_DEVAUC)
round[i] = ar + dr * urand (seed)
else {
s = sin (HALFPI * urand (seed))
round[i] = sqrt (s**2 * .99 + .01)
mag[i] = mag[i] + alpha * (1 / max (0.1, s) - 1) / 9.
}
}
end
# ST_PHI -- Compute an array of position angles.
procedure st_phi (phi, nstars, seed)
real phi[ARB] # array of position angles
int nstars # number of stars
long seed # seed for random number generator
int i
real urand()
begin
do i = 1, nstars
phi[i] = urand (seed)
call amapr (phi, phi, nstars, 0.0, 1.0, 0.0, 360.0)
end
# ST_DIAMETERS -- Compute the effective diameters of the galaxies based
# on their magnitudes. The relation used is from Holmberg (Stars and
# Stellar Systems). A uniform dispersion of 20% is added.
procedure st_diameters (mag, egal, axis, nstars, minmag, maxmag, eradius,
sradius, seed)
real mag[ARB] # input array of magnitudes
int egal[ARB] # array of galaxy types
real axis[ARB] # output array of diameters
int nstars # number of stars
real minmag # minimum magnitude
real maxmag # maximum magnitude
real eradius # maximum elliptical radius
real sradius # maximum spiral radius
long seed # seed for random number generator
int i
real urand()
begin
do i = 1, nstars {
if (egal[i] == ST_DEVAUC)
axis[i] = eradius * 10.0 ** ((minmag - mag[i]) / 6.)
else
axis[i] = sradius * eradius * 10.0 ** ((minmag - mag[i]) / 6.)
axis[i] = axis[i] * (0.8 + 0.4 * urand (seed))
}
end
# ST_ZDIAMETERS -- Compute the effective diameters of the galaxies based
# on their magnitudes and redshift. The relation used is that the redshift
# is proportional to the luminousity and the diameters include the
# factor of (1+z)**2. A uniform dispersion of 50% is added.
procedure st_zdiameters (mag, egal, axis, nstars, minmag, maxmag,
z, eradius, sradius, seed)
real mag[ARB] # input array of magnitudes
int egal[ARB] # array of galaxy types
real axis[ARB] # output array of diameters
int nstars # number of stars
real minmag # minimum magnitude
real maxmag # maximum magnitude
real z # minumum redshift
real eradius # maximum elliptical radius
real sradius # maximum spiral radius
long seed # seed for random number generator
int i
real z0, z1, urand()
begin
z0 = z / (1 + z) ** 2
do i = 1, nstars {
z1 = z * 10.0 ** (-0.2 * (minmag - mag[i]))
if (egal[i] == ST_DEVAUC)
axis[i] = eradius * z0 * (1 + z1) ** 2 / z1
else
axis[i] = sradius * eradius * z0 * (1 + z1) ** 2 / z1
axis[i] = axis[i] * (0.5 + urand (seed))
}
end
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