# In left- or right-rotation for arrays, where did those conventions for the directions come from?

This is a repost from another exchange.

I was going to write a paper about code to rotate elements in an array, but I realized I have no idea why rotation towards the start of the array is “left” and “right” goes towards the end. I’ve seen horizontal tape diagrams of arrays, with elements going left-to-right (i.e. Western-culture reading order), but I don’t know if that’s the actual reason.

Maybe finding out who first came up with the convention would help.

• ?? perhaps because English is written left-to-right, and therefore a list $[a,b,c,d,e]$ is written with the "start" on the left and the "finish" on the right. As you said. But of course, to answer this we need references not speculation. – Gerald Edgar Mar 7 at 14:21