• Yesterday, 16:31
We consider the boundary problem \begin{align*}-&y''(x)=0 \ \ \text{ for } \ x\in \Omega:=(0,\pi) \\ &y(0)=y(\pi)=0\end{align*} Let's pick the grid...
16 replies | 396 view(s)
• Yesterday, 14:11
Yes. And it also assumes we take $\nu=2$ steps with the damped Jacobi method. (Nod) It's not quite clear from the text to me. With a choice...
16 replies | 396 view(s)
• Yesterday, 12:43
Ahh I thought that at the proposition 8.9.13 (pg. 365) they would mean that we can get a good approximation for the error, but now I read that again...
16 replies | 396 view(s)
• Yesterday, 12:19
We can freely choose to use $\omega=2/3$ or a different $\omega$, or not use the damped Jacobi method at all. The chapter explains that it's giving...
16 replies | 396 view(s)
• Yesterday, 11:47
Ah ok! Do we take $\omega=2/3$ only at the 2-grid or in general? (Wondering) Could you give me a specific example where we can apply the method...
16 replies | 396 view(s)
• Yesterday, 06:19
Thanks steenis ... No worries at all ... Thanks for all your help ... Peter
10 replies | 163 view(s)
• Yesterday, 06:06
If $A$ and $B$ are nonempty sets of complex numbers, define $$A\circ B\ =\ \{z_1z_2:z_1\in A,\,z_2\in B\}.$$ Further define $A^{}=A$ and...
0 replies | 29 view(s)
• Yesterday, 06:04
Thanks Steenis ... That proof seems really clear ... Will work through it again shortly... Peter
4 replies | 73 view(s)
• Yesterday, 05:28
I would say build it up slowly, using concrete examples they can all understand. The simplest example would be clock arithmetic as time is surely...
1 replies | 75 view(s)
• Yesterday, 05:18
Sorry Steenis ... I don't understand you ... Can you give me a hint as to what is wrong ...? Peter
10 replies | 163 view(s)
• Yesterday, 04:51
Thanks steenis ... most helpful ... Can see that the short exact sequence $0\rightarrow \text{ker } f \overset{i}{ \rightarrow}R^{(n)}... 10 replies | 163 view(s) • Yesterday, 01:22 ======================================================================== Since I could not see any specific errors, I have completed the proof... 4 replies | 73 view(s) • June 17th, 2018, 18:01 At the last point why do we have that$f$and$g$are locally inverses of each other? What exactly does this mean? Also we have that$f\in...
3 replies | 68 view(s)
• June 17th, 2018, 14:46
I have thought of the following algorithm: We put an antenna $k$ meters east of the westernmost house. We continue to the east, by placing an...
1 replies | 36 view(s)
• June 17th, 2018, 12:39
MarkFL replied to a thread [SOLVED] 2.2.3 de with tan x in Differential Equations
I can't imagine trying to use the internet on a telephone. I'm sorry scrolling on a telephone is such a chore...they should fix that.
8 replies | 106 view(s)
• June 17th, 2018, 11:00
Hello!!! (Wave) We consider a long country road with $n$ houses placed along of it (we think of the road as a big line segment). We want to put...
1 replies | 36 view(s)
• June 17th, 2018, 10:37
Hey!! :o I want to show the following: Let $G \subset \mathbb{R}^n$ be open, $f \in C^1(G)$ and $\det J_f(x) \neq 0$ for all $x \in G$. Then...
3 replies | 68 view(s)
• June 17th, 2018, 05:04
Peter started a thread Deveno ... in Chat Room
Deveno is much missed ... especially by those who frequent the Linear and Abstract Algebra Forum ... Deveno's pedagogical abilities were as...
0 replies | 42 view(s)
• June 17th, 2018, 04:40
I am reading Dummit and Foote's book: "Abstract Algebra" (Third Edition) ... I am currently studying Chapter 10: Introduction to Module Theory ......
4 replies | 73 view(s)
• June 17th, 2018, 00:59
MarkFL replied to a thread [SOLVED] 2.2.3 de with tan x in Differential Equations
Are you using Tapatalk by any chance? I have code in place to let me know when posts have been edited, so I don't miss added content (it's better to...
8 replies | 106 view(s)
• June 17th, 2018, 00:52
MarkFL replied to a thread [SOLVED] 2.2.3 de with tan x in Differential Equations
When you multiply by $\mu(x)$, you get: \sec(x)y'+\tan(x)\sex(x)y=\sec(x)\sin(2x) This can be written as: ...
8 replies | 106 view(s)
• June 16th, 2018, 23:10
Thanks Steenis ... You have shown that $R^{(n)} / N \cong M$ where $N = \text{ Ker } f$ ... ... ... ... ... (1) ... and we have by...
10 replies | 163 view(s)
• June 16th, 2018, 19:51
MarkFL replied to a thread [SOLVED] 2.2.3 de with tan x in Differential Equations
-\ln(\cos(x))=\ln\left((\cos(x))^{-1}\right)=\ln(\sec(x))
8 replies | 106 view(s)
• June 16th, 2018, 19:38
MarkFL replied to a thread [SOLVED] 2.2.3 de with tan x in Differential Equations
\mu(x)=\exp\left(\int \tan(x)\,dx\right)=e^{\Large\ln(\sec(x))}=\sec(x)
8 replies | 106 view(s)
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