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## #1 2018-08-03 20:50:46

Hannibal lecter
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Registered: 2016-02-11
Posts: 225
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### A line is neither concave up nor concave down. what is that line

A line is neither concave up nor concave down.

what is that line, can I see a picture for it
I know the meaning of concave up and concave down.
but not others

Wisdom is a tree which grows in the heart and fruits on the tongue

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## #2 2018-08-04 15:21:52

George,Y
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Registered: 2006-03-12
Posts: 1,332

### Re: A line is neither concave up nor concave down. what is that line

a straight line would satisfy these criteria

if concavity = second derivative of the single variable function

X'(y-Xβ)=0

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## #3 2018-08-05 15:23:03

benice
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Registered: 2010-06-10
Posts: 116
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### Re: A line is neither concave up nor concave down. what is that line

Definitions of convex and concave functions (Wikipedia):

︶ Convex (= convex down = concave up) function

︵ Concave (= convex up = concave down) function

According to the definitions above, we have:

1. All non-vertical lines (y = ax + b) are both concave up and concave down;

2. A vertical line (x = c) is neither concave up nor concave down.

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