1 files changed, 59 insertions, 0 deletions
diff --git a/astro/cosmo_calc/calc_distance.h b/astro/cosmo_calc/calc_distance.h
new file mode 100644
index 0000000..a1f3352
--- /dev/null
+++ b/astro/cosmo_calc/calc_distance.h
@@ -0,0 +1,59 @@
+// calc_distance.h
+// calculate commonly used cosmology distances
+// Ref: https://en.wikipedia.org/wiki/Distance_measures_(cosmology)
+//
+// Junhua Gu
+//
+// ChangeLogs:
+// 2012/08/12, LIweitiaNux
+//   fix a bug in `calc_angular_distance()'
+//   add `calc_transcomv_distance()' and
+//     account `omega_k >0, <0' cases
+//
+
+#ifndef CALC_DISTANCE_H
+#define CALC_DISTANCE_H
+
+double cm=1.0;
+double s=1.0;
+double km=1000*100*cm;
+double Mpc=3.08568e+24*cm;
+double kpc=3.08568e+21*cm;
+double yr=365.*24.*3600.*s;
+double Gyr=1e9*yr;
+double arcsec2arc_ratio=1./60/60/180*3.1415926;
+double c=299792458.*100.*cm;
+
+// cosmology parameters
+double H0=71.0;         // units: [km/s/Mpc]
+double omega_m=0.27;
+double omega_l=0.73;
+double omega_k=1.0-omega_m-omega_l;
+
+// precision to determine float number equality
+double eps=1.0e-7;
+
+// open functions
+//
+// dimensionless Hubble parameter
+extern double E(double z);
+// Hubble distance
+extern double calc_hubble_distance(void);
+// calc `comoving distance'
+extern double calc_comoving_distance(double z);
+// calc `transverse comoving distance'
+extern double calc_transcomv_distance(double z);
+// calc `angular diameter distance'
+// d_A(z) = d_M(z)/(1+z)
+extern double calc_angdia_distance(double z);
+// calc `luminoisity distance'
+// d_L(z) = (1+z)*d_M(z)
+extern double calc_luminosity_distance(double z);
+// calc `light-travel distance'
+// d_T(z) = d_H \int_0^z 1/((1+z)*E(z)) dz
+extern double calc_ligtrav_distance(double z);
+
+#endif /* CALC_DISTANCE_H */
+
+//EOF
+/* vim: set ts=8 sw=4 tw=0 fenc=utf-8 ft=cpp: */