Are the following Mathematica codes correct for solving wave equation PDE?

I wanna solve the following PDE of wave equation using Mathematica.

$ u_{tt}=u_{xx}$

$ 0<x<\pi , t>0$

Initial Conditions:

$ \begin{cases}u(x,0)=sin(x) \u_{t}(x,0)=1\end{cases}$

Boundary Conditions:

$ \begin{cases}u(0,t)+u_{x}(0,t)=1\u(\pi,t)+u_{x}(\pi,t)=-1\end{cases}$

  • I know the boundary and initial conditions are inconsistent.

Are the following codes correct?

weqn = D[u[x, t], {t, 2}] == D[u[x, t], {x, 2}]; ic = {u[x, 0] == Sin[x],Derivative[0, 1][u][x, 0] == 1 }; bc = {u[0, t] + Derivative[1, 0][u][0, t] == 1,     u[Pi, t] + Derivative[1, 0][u][Pi, t] == -1}; sol = NDSolve[{weqn, ic, bc}, u, {x, 0, Pi}, {t, 0, 10}]; 

How to write currency codes for cryptocurrencies?

For “normal” currencies there is usually a sign (e.g. $ , €) and a code (e.g. USD and EUR) to denote that a number is a monetary value. Depending on your locale setting the sign can be written before or after the amount (variously) and the code (correct me if I’m wrong) can be written strictly only on one side or the other. For example, in Sweden we write 10€ and 10 EUR but in the UK they write €10 and EUR 10.

My question is: how it should be treated in the world of cryptocurrencies? Those currencies don’t have any symbols, only codes (depends on how you see it). Should they be treated as “real” currencies and have the code placed depending on localization? I’m confused because I’ve never encountered any situation where it’s written ETH 10 instead of 10 ETH.

VOIP providers that provide support to receiving SMS from short codes?

I had a Canadian phone number and I started to travel frequently so I ported it to a VOIP provider. I still needed the phone number because a lot of online services I used relied on two factor authentication. Later, I realized that the VOIP provider I subscribed to doesn’t support receiving SMS from shortcodes (the numbers from which 2FA services send out codes to verify the phone number) so now either I can’t sign in, or I choose the voice call option when available to login to these services. Is there a VOIP provider that supports receiving SMS from short codes?

Confusing notation in concatenation of error correcting codes

Define an $ (m,q,d,k)$ -(block) code $ C$ to be a code with block size $ m$ , alphabet $ 0\ldots ,q-1$ , and (non-relative) rate $ k$ . Meaning: $ k=log_q (|C|)$ (if we think of $ C$ as a set of legal codewords) ($ d$ is the distance which isn’t important for this particular question). Such a code could also be thought of as a function: $ $ C:[q]^k\rightarrow[q]^m$ $ As it takes a word of length $ k$ over $ [q]$ and encodes it into a word of length $ m$ .

To my understanding, given an $ (m,q,d,k)$ code $ C_{out}$ and an $ (m’,q’,d’,k’)$ code $ C_{in}$ such that $ q’^{k’}=q$ , we can define the concatenation of $ C_{out}$ with $ C_{in}$ to be a code which takes an input for $ C_{out}$ , encodes it using $ C_{out}$ , and then encodes each letter of the resulting word using $ C_{in}$ . If this is how a concatenated code truly works, then if we denote the concatenated code $ C’$ it should be thought of as a function: $ $ C’:[q]^k\rightarrow [q’]^{m*m’}$ $ However, the common notation for such a codes (as can be seen here, for example) is: $ $ C_{out}\circ C_{in}$ $ Which is exactly in the opposite order to what we would expect if we think about the concatenated code as a composition of functions.

Is there a problem with my understanding of concatenated codes, or is the notation simply confusing? And if my understanding is good, is there a reason the aforementioned notation is common?

Best 2 codes for understanding how Magento frontend works

I’m new to Magento. I’m working in 1.9 and playing in 2.4.

I am an intermediate level in HTML5, CSS3. I have a light understanding of using the Magento CMS and concepts of OOP.

My strength is in design concepts, color, composition…

I love coding, so I started out trying to learn php and xml from scratch to understand how magneto works. While I was enjoying it, it started to get too far removed from my desired path. At this point I see my path in frontend with theming, Jquery, Canvas and JS to get a feel for how Magento front end works.

What should I start to learn first as a code path that will help me the most for Magento?

Do I need to understand PHP and XML extensively if I am not working in the data base?

To what extent should I know PHP and XML?

How do modules work in Magento ?

Thank you so much for your professional and expert knowledge!

UPC Codes for FBA

Hi guys,

I was wondering if it is advised to send your UPC codes to the supplier in China so they can affix it to each unit before shipping to you? Many training videos I've watched attach the UPC codes after the products arrive at the owners address, however I've seen a few videos that imply you should give the supplier the UPC codes to attach to each unit before sending to your US address.

Is this not typically what Amazon FBA Prep Centers are for? Just wanted some clarification. Much…

UPC Codes for FBA

How to transfer IR Remote codes to a phone which has no learning support?

My current Android phone (Oreo 8.1) has got an IR sensor and I can use it to control some devices. But unlike, my old Android phone (KitKat 4.4), it doesn’t support learning new IR codes to act as a universal remote. Fortunately , I have still got my old phone with me. Is it possible to transfer the IR code files learned by my old device to new device?

How do I do this, if it is possible?

What do all those cryptic number and letter codes in a lens name mean?

When looking at a lens name, there are a lot acronyms describing its features (often specific to the manufacturer).

Examples, Nikon:
Nikon AF-S DX 16-85mm VR f/3.5-5.6G IF-ED
Nikon AF-I 600mm f/4D IF-ED
Nikon AF-S VR Micro-NIKKOR 105mm f/2.8G IF-ED

Examples, Canon:
Canon EF 85mm f1.2L USM Mark II
Canon 70-300mm f/4.5-f/5.6 DO IS

Examples, Sigma:
Sigma 150mm F2.8 EX APO DG HSM Macro
Sigma 70-200mm F2.8 EX DG OS HSM
Sigma 50-150mm F2.8 EX DC APO HSM II

How do I decipher these lens codes from different manufacturers?

What are the manufacturer codes for rebranded lenses?

Many off-brand lenses were made by the same set of manufacturers, and some brands served primarily as redistributors. For instance, Vivitar lenses were generally manufactured by others. In some cases, the original manufacturer is encoded in the serial number. With the exception of Vivitar, manufacturer codes do not appear to be readily available online (at least they do not come up in top search results).

What were the manufacturer codes used by other redistributors?

  • Sears
  • J.C. Penney
  • Focal (K-Mart)
  • etc.