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  • 18 votes cast
Jan
12
accepted Understanding meaning of $f''$ for $x^2$ and $x^4$
Jan
10
comment Understanding meaning of $f''$ for $x^2$ and $x^4$
Apologies, yes, I meant the 2nd derivative is constant.
Jan
10
comment Understanding meaning of $f''$ for $x^2$ and $x^4$
I understand your 1st and 2nd paragraphs, and that helps, so thank you. I now understand that $x^2$ and $x^4$ look the same only superficially. I don't understand your 3rd paragraph however.
Jan
10
comment Understanding meaning of $f''$ for $x^2$ and $x^4$
Aaaaaahhh, that would explain the concavity thing. The red line is a constant curvature, the blue one is not! Gotcha. Thank you
Jan
10
comment Understanding meaning of $f''$ for $x^2$ and $x^4$
@Daniel I know!
Jan
10
comment Understanding meaning of $f''$ for $x^2$ and $x^4$
@BenLongo I didn't mean the function is increasing but that the gradient is.
Jan
10
comment Understanding meaning of $f''$ for $x^2$ and $x^4$
What is wrong with saying that $y''>0$ means the gradient is increasing?
Jan
10
asked Understanding meaning of $f''$ for $x^2$ and $x^4$
May
10
awarded  Commentator
May
10
comment What does the last range on a histogram represent?
@Casteels "not really a precise mathematical construct" Ah, OK, got it! Cheers. "adding that extra end-point does not change the width" confuses me though, or are you just saying a point has no width by definition? I get that.
May
10
comment What does the last range on a histogram represent?
@Casteels The author is asking me to decide what the other groups are. The one you have suggested makes sense as $m$ can be equal to 100. However, this does not follow the pattern. Is it fair to just change the last group so that it 'makes sense'? Is it normal that we just go ahead and change the last group?
May
10
revised What does the last range on a histogram represent?
added 97 characters in body
May
10
asked What does the last range on a histogram represent?
Sep
24
awarded  Autobiographer
Mar
22
awarded  Cleanup
Mar
9
comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)
What was their answer?
Feb
12
comment What is a diffeomorphism?
Sorry Muphrid but I can't accept your answer since I don't have enough rep here, I +1'd it though. I don't know why the question was migrated, I was only looking for a hand-wavy definition.
Jan
22
answered The triangle inequality for integrals
Jan
20
comment How does one create a rotation about a given axis in $R^{3}$ from rotations about the other axes?
This seemed to do the trick. Thanks @Shard !
Jan
20
comment How does one create a rotation about a given axis in $R^{3}$ from rotations about the other axes?
While it is a very nice result, I'm not sure it actually answers the question in that the matrix $\bf{R_{\hat{u}}}$ would appear difficult to decompose.