I have an ellipse which has -45 degree axis.

How can I transform the ellipse into a circle? Can I use shear transformation along the x/y axis?

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  • $\begingroup$ Do you just require the outcome to be a circle (any size circle), or does the diagram indicate that you require specifically that size circle from that size ellipse? $\endgroup$ Commented Apr 18, 2019 at 20:40
  • $\begingroup$ The circle size can be arbitrary size. I just want the transformed into complete circle. thank you very much. $\endgroup$ Commented Apr 19, 2019 at 1:33

1 Answer 1


You can use a shear, or equivalently a rotation by 45, scale along one of the axes, rotate back (which is equivalent to the shear which you are looking for).

EDIT: On second thought, you don't need to even rotate back unless your circle is marked, since a circle is rotation invariant (if the rotation is around its center).


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