Yes. The equation of an ellipse aligned with the X-axis is
Code:
(x/a)^2 + (y/b)^2 == 1
That means you are scaling (tilting) the x-axis by 1/a and the y-axis by 1/b. If you undo the tilting you get:
Code:
x' = x/a
y' = y/b
x'^2 + y'^2 == 1
That is the equation of a unit circle.