22,867 reputation
33979
bio website
location
age
visits member for 2 years, 10 months
seen 9 hours ago

9h
comment What exactly are divided Differences?
The derivative of a function gives you the slope of that function, right? But a derivative can be complicated to compute. Another way to estimate the slope is to pick two points and estimate the slope linearly, using the good ol' "rise-over-run" formula. That is, you divide the difference of the change of the function over the difference of the change over its arguments.
1d
reviewed Close Orthogonality and Kernel
1d
reviewed Close Find the Fourier Coefficients that minimize the error
1d
reviewed Leave Open Calculating points in an arc
1d
reviewed Leave Open Dimension of a vector space with linearly independent vectors
1d
reviewed Close Theory automata. Proof.
1d
answered Matlab upper and lower triangular matrix
1d
reviewed Close True or False : For any 2x2 matrix, rank(A) = rank(A transpose)
1d
comment Probability density funciton from CDF - one step in derivation
Oh, I see you wrote something about $r(x)$ being an infinitesimal. Think of $r(x)$ as a thing that goes to zero faster than $\Delta x$. It comes from the definition of the derivative as a linear approximation in a local neighborhood. There are several ways to interpret this that are more or less equivalent.
1d
comment Probability density funciton from CDF - one step in derivation
Does the book give you any other properties of $r(x)$, such as $r(x) = 0$ on the support of $dF(x)$, or something similar?
1d
comment Multiplication of three discrete-time MIMO systems in matlab
Are $A_1, B_1$, etc. matrices or real scalar values?
1d
answered Why we write $z=x+iy$?
2d
comment finding lambda in a poisson distribution
It should be a $P\{X = 2\}$... "the probability the frog jumps twice."
2d
asked Measure-theoretic conditional expectation
2d
comment For positive measures $\nu_j$, is $\left(\sum_1^\infty \nu_j\right)(E) \le \sum_1^\infty \nu_j(E)$?
@copper.hat In such a case, I wish I had back my restless 45 minutes of overthinking this problem last night.
2d
awarded  Enlightened
2d
comment For positive measures $\nu_j$, is $\left(\sum_1^\infty \nu_j\right)(E) \le \sum_1^\infty \nu_j(E)$?
@copper.hat I guess it must be. I will have to explore where finiteness is used in other proofs, as my approach seems to be identical but does not require that property.
2d
comment For positive measures $\nu_j$, is $\left(\sum_1^\infty \nu_j\right)(E) \le \sum_1^\infty \nu_j(E)$?
In other words, is $\left(\sum_1^\infty \nu_j\right)(E) = \sum_1^\infty \nu_j(E)$ by definition and I am just being daft? Unfortunately, I cannot find this notation defined in my textbook.
2d
revised For positive measures $\nu_j$, is $\left(\sum_1^\infty \nu_j\right)(E) \le \sum_1^\infty \nu_j(E)$?
added 9 characters in body; edited title
2d
comment For positive measures $\nu_j$, is $\left(\sum_1^\infty \nu_j\right)(E) \le \sum_1^\infty \nu_j(E)$?
@copper.hat Since $\sum_1^\infty \nu_j$ is a measure, $\left(\sum_1^\infty \nu_j\right)(E)$ denotes that measure of the set $E$. If it is simpler, let $\lambda = \sum_1^\infty\nu_j$; I need to explore $\lambda(E)$.