Mass, Tidal and Velocity field in Sloan Digital Sky Survey volume (SDSS_MTV for short)

File name                              quantity                                                  unit
Fillingfactor_sdssMth12_80Mpc       F, filling factor                                       non, |F|<=1
MDen_sdssMth12_Ms13               delta, overdensity=(rho_i-rho_ave)/rho_ave                non
Velx_sdssMth12_Ms13               Vx, X component of Velocity                               km/s 
Vely_sdssMth12_Ms13               Vy, Y component of Velocity                               km/s
Velz_sdssMth12_Ms13               Vz, Z component of Velocity                               km/s
Tid1_sdssMth12_Ms13               T1, the eigenvalue of tidal tensor along major axis       [km/s/(Mpc/h)]^2 
Tid2_sdssMth12_Ms13               T2, the eigenvalue of tidal tensor along inter axis       [km/s/(Mpc/h)]^2        
Tid3_sdssMth12_Ms13               T3, the eigenvalue of tidal tensor along minor axis       [km/s/(Mpc/h)]^2        

Notes: 
1 see Wang et al. 2011 (arXiv:1108.1008) for the details on how these values are derived.
2 the smoothing kernel is Gaussian kernel and the smoothing mass scale is 10^13 Msun/h.
3 the ABSOLUTE value of F on a grid is the filling factor of the grid. If F>0, the grid is within the survey volume, 
otherwise, this grid is outside the survey volume.
4 all eight files are in the same format, which can be read using the following C and Fortran routines.


Please acknowledge us and reference our papers if you use any SDSS_MTV data.


=========================================================================================================
reading routines:

---------------------------------------------------------------------------------------------------------

C program:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int main()
(
    int i,xid,yid,zid;
    int Nx,Ny,Nz,itemp;
    float *quan,pos[3],rp;
    FILE *fp;
    char filename[256];
    
    sprintf(filename,"Fillingfactor_sdssMth12_80Mpc");
    
    Nx=494;
    Ny=892;
    Nz=499;
    
    rp=726.0/1024;
    
    quan=(float *)malloc(Nx*Ny*Nz*sizeof(float));
    
    fp=fopen(filename,"r");
    fread(&itemp,1,sizeof(float),fp);
    if(itemp/sizeof(float) != Nx*Ny*Nz)
    {
        printf("error! itemp=%d\n",itemp);
        exit(1);
    }
    fread(quan,sizeof(float),Nx*Ny*Nz,fp);
    fclose(fp);
    
    for(i=0;i<Nx*Ny*Nz;i++)
    {
    	xid=i/Ny/Nz;
    	yid=i/Nz-xid*Ny;
    	zid=i-(xid*Ny+yid)*Nz;
    	pos[0]=xid*rp-351.016602;
    	pos[1]=yid*rp-329.688477;
    	pos[2]=zid*rp-22.725586;
    	
    	printf("the position of grid %d is %f %f %f (in unit of Mpc/h)\n",i,pos[0],pos[1],pos[2]);	
    }
/*    your code here */

}

---------------------------------------------------------------------------------------------------------

Fortran program:
       
       program readf
       integer i,Nx,Ny,Nz,xid,yid,zid
       real rp,pos(3)
       real,allocatable :: quan(:)
       character dumpf*256
       
       write(dumpf,'(''Fillingfactor_sdssMth12_80Mpc'')')

       Nx=494
       Ny=892
       Nz=499
       
       rp=726.0/1024
       
       allocate(quan(0:Nx*Ny*Nz-1))
       
       open(10,file=dumpf,status='unknown',form='unformatted')
       read(10) quan
       close(10)
       
       do i=0, Nx*Ny*Nz-1
       
 	   xid=i/Ny/Nz;
	   yid=i/Nz-xid*Ny;
	   zid=i-(xid*Ny+yid)*Nz;
	   pos(1)=xid*rp-351.016602;
	   pos(2)=yid*rp-329.688477;
	   pos(3)=zid*rp-22.725586;           
           
           write(*,*) "the position of grid ",i, "is ", 
     &      pos(1),pos(2),pos(3), "(in unit of Mpc/h)"
           
       enddo
       
!      your code here ............
       
       end
=========================================================================================================