d_rndzsmail.c
c99f2e455a51preparemerge

d_rndzsmail.c
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			#include<math.h>
			#include<fonction.h>

			/* -------------------------------------------------------------------
			generate a redshift for a source following a Smail et al. distribution
			------------------------------------------------------------------*/

			// Sampling of the Smail et al. function. Make sure this number is significantly larger
			// than your sample of objects for which you want to get a redshift, so
			// that each return redshift is unique
			#define KSMAIL 1000

			// Return a pointer to a structure that help speedup the following calculations
			// (see gsl: General-Discrete-Distributions.html)
			gsl_ran_discrete_t* smailpreproc()
			{
			extern struct g_source S;
			int i;
			double z, p[KSMAIL];

			// Compute the Smail et al. array in [zsmin, zsmax]
			for( i = 0; i < KSMAIL; i++ )
			{
			z = S.zsmin + i * (S.zsmax - S.zsmin) / (KSMAIL-1);
			p[i] = pow(z, S.par1) * exp(-pow(z/S.par2, S.par3));
			}

			return gsl_ran_discrete_preproc(KSMAIL, p);
			}

			/* Return a redshift validating the Smail et al. function defined with parameters
			* in g_source structure.
			* Input :
			* - r : random seed
			* - g : gsl structure obtained from smailpreproc()
			*/
			double d_rndzsmail(gsl_rng * r, gsl_ran_discrete_t * g)
			{
			extern struct g_source S;
			size_t i;
			double zrnd;

			i = gsl_ran_discrete (r, g);
			zrnd = S.zsmin + i * (S.zsmax - S.zsmin) / (KSMAIL - 1);

			return zrnd;
			}