Hi, I am using the code yt.lagrangian_volume to trace the box that contains the dark matter particles at an early stage(higher redshift). But I was quite confused about the output. I am attaching the output file below. (1) I don't know what the values for the box in the new frame mean, i.e. what is the unit of these values? It seems to be the normalized scale because the values are about 1. But it does not seem to be normalized too because there are some values that are larger than 1. Is that due to the periodicity of the box? (2) The bounding box and box in the new frame seems to have the same size. The difference between the two box is just translation. But I was expecting that the box should be expanding/collapsing. (3) The COM (center of mass) in the output is within neither of the box. Does anyone know how to explain the box values in the output file? Thanks, Jingjing -- Jingjing Chen [ chenjj235@gmail.com ] Department of Astronomy Columbia University 550 West 120th Street New York, New York 10027 Cell Phone: +1(347)5746709