# trying to understand the "Step through memory only once"

Hi All,

I tried to understand " Technical report: How to implement your DdQq dynamics with
only q variables per node (instead of 2q)"the last days but there is question I don’t get answered myself. Any help would be highly appreciated.

On page 6 of the “Technical report: How to implement your DdQq dynamics with only q variables per node (instead of 2q)”,

The condition is that all velocities ci, for i = 1…(q-1)/2 verify the following

[i]In 2D (c[i][0] < 0)OR (c[i][0] = 0 AND c[i][1] < 0) (6)
In 3D (c[i][0] < 0) OR (c[i][0] = 0 AND c[i][1] < 0)
OR (c[i][0] = 0 AND c[i][1] = 0 AND c[2] < 0). (7)

What are there relationship between ci and c[i][0] (or [i]c[1],[i]c[2])?

Sorry to bother you guys but I really couldn’t understand that until now. Thanks in advance,

Sun Zhang

Sorry,I mistaken.

What are relationships between ci and c[i][0](or c[i][1],c[i][2])?

Thanks

Sun Zhang

c[i][0] is the x-component of ci, and so on.

Thank you Jonas! I have understand.