Matrix or single-array abstraction?

[Anvilfolk]

Right, so I've seen that a few people, instead of having a "real" matrix (as in, an array of arrays) use a single array, and when they want to access position (x, y) do something along the lines of array[x + y*width].

Is it really worth it? You're trying to trade two memory accesses for a single one with a little arithmetic on the side, right? Is that speed gain even significant?

Is there something I'm missing?

[stu]

well its easier to malloc(x*y) than malloc(x) for(j=0;j<x; j++) x[j]=malloc(y)

accessing x[y][z] vs x[y*q + z] makes no difference.

it isnt about speed, its conveniance.

it really makes no difference.

[Anvilfolk]

Gotcha, thanks!

Having started to use it, it's also a bit more fool-proof than trying to remember to use matrix[y]

• , which is still slightly counter-intuitive to me.