Horizontal Stretches/Compression (Math Question).

[Osc89]

Jay520 said:

Osc89 said:
It's to do with the absolute value of A, not whether it is positive or negative. I think it is a property of homogeneous functions, as -f(Ax) = f(-Ax), so it has to have that kind of symmetry

I see, It's just strange that horizontal stretches are based on absolute value rather than positive or negative, while vertical stretches, vertical shifts, and horizontal shifts are completely different. 

Never heard of homogeneous functions. Should I have?

Isn't a horizontal stretch just a vertical squish though? I'm pretty tired as it's late here so I can't really picture it, but I'm not sure the vertical transformations behave differently. I'm thinking of g(x) = Af(x) meaning the same as (1/A)g(x) = f(x), again only with homogeneous.

Homogeneous just means that you can put the scalar out, i.e. f(Ax) = Af(x). So for y=2x, or y=x^2 (except that homogeneous of degree 2 as the scalar is squared).