Voidfinder

Finds and quantifies empty space. Voidfinder is a Fortran subroutine that takes the position of galaxies in cartesian coordinates. Some subroutines used in the body of SDSSvoidfinder (the main program) are used to convert the ra, dec and redshift into comoving cartesian coordinates that the subroutine voidfinder understands.
Find Voidfinder at: http://www.carofoster.com/software