# Calc III type question: gradients, normal vectors, and the like

**URL:** <https://boards.straightdope.com/t/calc-iii-type-question-gradients-normal-vectors-and-the-like/118362>\
**Category:** Factual Questions\
**Created:** [July 11, 2002, 3:54am UTC](https://boards.straightdope.com/t/calc-iii-type-question-gradients-normal-vectors-and-the-like/118362 "2002-07-11T03:54:46Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\
**Post date:** [July 13, 2002, 3:05am UTC](https://boards.straightdope.com/t/calc-iii-type-question-gradients-normal-vectors-and-the-like/118362/21 "2002-07-13T03:05:45Z")

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I like the cut of your jib **Ring** , but would you mind explaining a little more detail of what you did? Specifically, what’s f? I would have imagined that f[sub]z[/sub] = 2z.

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**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\
**Post date:** [July 13, 2002, 2:09pm UTC](https://boards.straightdope.com/t/calc-iii-type-question-gradients-normal-vectors-and-the-like/118362/22 "2002-07-13T14:09:54Z")

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**Achernar** , I couldn’t possibly have been so stupid as to put that minus sign in there. It must have been someone else. Please help me track this malefactor down, a person this moronic shouldn’t be allowed to consume scarce planetary resources.

(God, it’s so sad – I’m such a lamebrain)

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