# Rotations from fast Transform sign flipping

**URL:** <https://discourse.processing.org/t/rotations-from-fast-transform-sign-flipping/49009>\
**Category:** Gallery\
**Created:** [July 19, 2026, 5:49am UTC](https://discourse.processing.org/t/rotations-from-fast-transform-sign-flipping/49009 "2026-07-19T05:49:07Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![seanc4s](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@seanc4s](https://discourse.processing.org/u/seanc4s)\
**Post date:** [July 19, 2026, 5:49am UTC](https://discourse.processing.org/t/rotations-from-fast-transform-sign-flipping/49009/1 "2026-07-19T05:49:07Z")

</div>

Often fast transforms are self-inverse. If you keep applying such a transform you get spread out form, input form, spread out form,input form…

If you mis-align ( sign flip) some values between the fast transforms you get rotations, often quite slow ones:

[https://editor.p5js.org/seanhaddps/sketches/ysKtMpyJS](https://editor.p5js.org/seanhaddps/sketches/ysKtMpyJS)