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Feb
22
revised Matrix rank inequality
deleted 2 characters in body; edited tags
Feb
22
answered $\sigma$-algebra generated by a subset
Feb
22
comment How to find second order derivative
when i posted an answer, i made a mistake in calculations, so i thought i well knew what the answer was. as for this comment, it is not an answer, just a suggestion along which lines i would think...
Feb
19
revised Taylor series expansion of $ f(x)=e^{-x^2}$
edited title
Feb
19
comment Proof that this distribution is N(0,1)?
@user270494 yes
Feb
18
comment Proof that this distribution is N(0,1)?
@user270494 depends on the form. In the most common form for a stochastic process $Z_n$ with mean $m$ and stdev $s$, we have $$\frac{\bar{Z}_n - m}{s/n} \to \mathcal{N}(0,1)$$
Feb
18
answered Proof that this distribution is N(0,1)?
Feb
18
revised Proof that this distribution is N(0,1)?
added 329 characters in body; edited tags
Feb
18
answered Identify the misprint in a sequence
Feb
18
comment How to find second order derivative
you are right. possibly you can proceed by analogy with 2D, taking a total differential of a sorts to get $d^2 p = u (dt)^2 + s (dz)^2$ and maybe using $dz^2 = dt$, but not sure how.
Feb
18
awarded  Generalist
Feb
17
comment Height of Isosceles Triangle
don't think so -- different heights are possible. you could find the range for the height though...
Feb
17
revised $f(x) = x\sin(1/x)$, $0 < x \le 1$, with $f(0) = 0$, is continuous on $[0, 1]$?
added 40 characters in body
Feb
17
comment Prove a connected graph has n-1 edges and has no cycle
may help to proceed by strong induction on $n$ and reduce the graph by removing a leaf if it exists.
Feb
17
answered How can I calculate, how the volume element transforms under change of co-ordinates?
Feb
17
revised How can I calculate, how the volume element transforms under change of co-ordinates?
added 61 characters in body; edited tags
Feb
17
reviewed Approve Cardinality of $X \cup Y$?
Feb
17
answered Cardinality of $X \cup Y$?
Feb
17
comment creating positive definite matrix using wishrnd in matlab
@sahar you can use my code to create the random positive definite matrix sigma you were asking about. The rest would work the way it is now.
Feb
16
comment Showing that a derivable function $f$ (satisfying some conditions) is null.
typically, Taylor's theorem is key for things like this, but not sure it will help here...