# Excel: How to make a curvefit to sin^4(x) in office 2007 - or any freeware to do it?

**URL:** <https://boards.straightdope.com/t/excel-how-to-make-a-curvefit-to-sin-4-x-in-office-2007-or-any-freeware-to-do-it/476613>\
**Category:** Factual Questions\
**Created:** [December 10, 2008, 9:32pm UTC](https://boards.straightdope.com/t/excel-how-to-make-a-curvefit-to-sin-4-x-in-office-2007-or-any-freeware-to-do-it/476613 "2008-12-10T21:32:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Tikster](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@Tikster](https://boards.straightdope.com/u/Tikster)\
**Post date:** [December 10, 2008, 9:32pm UTC](https://boards.straightdope.com/t/excel-how-to-make-a-curvefit-to-sin-4-x-in-office-2007-or-any-freeware-to-do-it/476613/1 "2008-12-10T21:32:59Z")

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I need to fit some data to a sine to the fourth and I can’t get a user defined option in excel (or maybe I’m blind?) - Any of you guys know how to do it or know of any freeware programs that can do the same?

Thanks!

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**Author:** ![Zany\_Zeolite\_Zipper](https://avatars.discourse-cdn.com/v4/letter/z/4af34b/32.png) [@Zany\_Zeolite\_Zipper](https://boards.straightdope.com/u/Zany_Zeolite_Zipper)\
**Post date:** [December 10, 2008, 9:56pm UTC](https://boards.straightdope.com/t/excel-how-to-make-a-curvefit-to-sin-4-x-in-office-2007-or-any-freeware-to-do-it/476613/2 "2008-12-10T21:56:10Z")

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If you need the model in the form of y = a (sin x)^4 + b you can simply plot y vs (sin x)^4 , but if you want a model in the form of y = a(sin wx + phi)^4 +b that is hard. Will this help: [Re: Sin Fit - NI Community](http://forums.ni.com/ni/board/message?board.id=170&message.id=236070)

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**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\
**Post date:** [December 10, 2008, 11:04pm UTC](https://boards.straightdope.com/t/excel-how-to-make-a-curvefit-to-sin-4-x-in-office-2007-or-any-freeware-to-do-it/476613/3 "2008-12-10T23:04:20Z")

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Excel sucks for statistics. Ideally you’d use [R](http://www.r-project.org) instead, but if you have a deadline, the learning curve might be an issue.

sin[sup]4/sup is sort of an unusual function to be regressing against. What makes you think that it’s the right model here?