482 reputation
37
bio website verbeia.com/mathematica/tips/…
location Maryland
age
visits member for 2 years, 2 months
seen Jan 11 at 1:57

BS Electrical Engineering, Penn State, 1987

MS Electrical Engineering, Florida Tech, 1994

Has been a devoted Mathematica user since 1989. Also, interested in numerical algorithms, functions of complex variables, and optimal design digital filters.


Feb
10
awarded  Yearling
Jan
6
accepted Generality of Lebesgue integration?
Jan
6
accepted Do we have a notation for a quantity that is smaller or larger than x by an infinitesimal amount?
Jan
6
asked Generality of Lebesgue integration?
Jan
6
comment Do we have a notation for a quantity that is smaller or larger than x by an infinitesimal amount?
@Stephen Montgomery-Smith, Make it an answer, and I will accept it.
Jan
6
comment Do we have a notation for a quantity that is smaller or larger than x by an infinitesimal amount?
@Han de Bruijn, Error is a totally different topic. Using the notation mentioned above by Stephen Montgomery-Smith "2+" is a quantity that is larger than 2 by an infinitely small amount. Also "2-" is smaller than 2 by an infinitely small amount. A useful application is ArcTan(0-) = -Pi/2.
Jan
5
comment Do we have a notation for a quantity that is smaller or larger than x by an infinitesimal amount?
@E.O. What's wrong with limits? Complicated things will be more readable if we have concise notation. We may have never found solutions to PDEs if the were expressed in terms of: For every epsilonX, epsilonY, there exists a deltaX, deltaY such that ....
Jan
5
asked Do we have a notation for a quantity that is smaller or larger than x by an infinitesimal amount?
Jan
5
accepted $\infty\pm\infty$ on a Riemann sphere
Jan
4
awarded  Supporter
Jan
3
comment $\infty\pm\infty$ on a Riemann sphere
@Christian Blatter, It makes sense to me to say<br> $z\cdot\infty = \infty$ for any complex non-zero $z$.<br> and the book Mathematical Analysis by Tom Apostol says this as well. Your second sentence agrees with this, but your first sentence says it is one of the things that are undefined. Please clarify.
Jan
3
revised $\infty\pm\infty$ on a Riemann sphere
added 377 characters in body
Jan
2
comment $\infty\pm\infty$ on a Riemann sphere
I like the explanation of "undefined" vs "indeterminate". That point has puzzled me for a few years. I am an electrical engineer with a strong interest in math.
Jan
1
comment $\infty\pm\infty$ on a Riemann sphere
@Michael Hardy, I like the precise definition of Indeterminate. All other explanations I have read are hand wavy.
Jan
1
comment $\infty\pm\infty$ on a Riemann sphere
I recall reading it in a text book I left at work. I will check the book when I get to work tomorrow. Although I see en.wikipedia.org/wiki/Riemann_sphere says Inf +- Inf are both undefined.
Jan
1
asked $\infty\pm\infty$ on a Riemann sphere
Dec
24
awarded  Popular Question
Apr
18
awarded  Scholar
Apr
18
accepted Trouble computing gradient of $\mid f(z) \mid^2$.
Apr
18
comment Trouble computing gradient of $\mid f(z) \mid^2$.
I see a problem there cause Conjugate(z) is not differentiable. However, I really do want derivatives WRT (a0, a1, b0, b1) as the purpose is to find optimal values of those variables. The gradient is very useful for that. The good news is that you pointed out that abs(H(z))^2 = H(z) conjugate(H(z)) = H(z) H(conjugate(z)). From there it's easy. .... All in ASCII since I am sending from my iPhone.