beginning to fold in HOD code with jeremy tinker's approval

c_tools/hod/mstar.c

@@ -0,0 +1,39 @@
+#include <stdlib.h>
+#include <math.h>
+#include <stdio.h>
+#include "header.h"
+
+/* This function calculates M_star (non-linear mass scale) for the given
+ * cosmological paramters.
+ */
+
+double sigma_Mmdelta_c(double lnM);
+double pnorm1;
+
+double mstar()
+{
+  double sig,lnMmin,lnMmax,M_star;
+
+  sig=sigmac(8.0); 
+  pnorm1 = SIGMA_8/sig;
+  
+  lnMmin=log(1e7);
+  lnMmax=log(1e18);
+  M_star=zbrent(sigma_Mmdelta_c,lnMmin,lnMmax,1e-5);
+  M_star=exp(M_star);
+  if(!ThisTask)
+    fprintf(stderr,"M_star = %e h^{-1}M_sol\n",M_star);
+  return(M_star); 
+}
+
+/*** solve for M_* ***/
+double sigma_Mmdelta_c(double lnM)
+{ 
+  double sig,M,rm;
+
+  M=exp(lnM);
+  rm=pow(3.0*M/(4.0*PI*OMEGA_M*RHO_CRIT),1.0/3.0);
+  sig=pnorm1*sigmac(rm);
+
+  return sig-DELTA_CRIT;
+}