  A computer code to simulate temporal evolution of overdensities in a
one-dimensional Universe is presented for didactic purposes. The formation of
large scale structures in this one-dimensional universe can be studied both in
matter or radiation dominated eras. Since large scale structures are already
observed at z > 7, primordial dark matter overdensities delta_DM which are 90
times larger than the observed barionic delta_B in the cosmic microwave
background are required at z~1000. This makes possible non-linear gravitational
collapse at redshift z >7 and the formation of the structures. Primordial
perturbations delta_B~10^-5 do not leave the linear regime of growth without
the aid of dark matter's potential wells. This code is suitable for commercial
worksheets like MSExcel, StarOffice, or OpenOffice.
