How many cubelets need to be transparent between two interferometer cubelets, whose coordinates are $[x_1,y_1,z_1]$ and $[x_2,y_2,z_2]$?
Noting the absolute distances for each coordinate with $[d_x,d_y,d_z]=[|x_1-x_2|,|y_1-y_2|,|z_1-z_2|]$ the answer for this is something like $d_x+d_y+d_z-\gcd(d_x+1,d_y+1)-\gcd(d_x+1,d_z+1)-\gcd(d_y+1,d_z+1)+2\gcd(d_x+1,d_y+1,d_z+1)$, where $\gcd(\cdot)$ notes the greatest common divisor.
This expression relies on the fact that among the transparent cubelets thereThis expression relies on the fact that among the transparent cubelets there have to be one for each of the $x$ coordinate range between $x_1$ and $x_2$ ($d_x-1$), and also for the other two coordinates. (analogous expression with $d_y$ and $d_z$ instead of $d_x$) For each coordinate-pair, we have to subtract the amount of edge-crossings ($\gcd(d_x+1,d_y+1)-1$ and analogous expressions), but then we have counted corner-crossings ($\gcd(d_x+1,d_y+1,d_z+1)-1$) three times, so we have to add the double of that amount back. But I'm not sure in this last term, and the expression seems to have some error in some cases.
Ok, I have to be one for each of the $x$ coordinate range between $x_1$ and $x_2$ ($d_x-1$), and also for the other two coordinatesthink this through. (analogousAlthough this expression with $d_y$ and $d_z$ instead of $d_x$) For each coordinate-pair, we have to subtract the amount of edge-crossings ($\gcd(d_x+1,d_y+1)-1$ and analogous expressions), but then we have counted corner-crossings ($\gcd(d_x+1,d_y+1,d_z+1)-1$) three timesworks well for estimation, so we have to add the double of that amount backit is far from being correct. But I'm not sure in this last term, and the expression seems to have some error in some casesworking on cleaning it.