calculations – Calculate lens FOV difference between Full-frame and APS-C sensors?

Shuttermuse has a rudimentary formula, but ScanTips has a more detailed explanation as well as a calculator.

In general, you can take the 35mm full-frame focal length and multiply it by the crop factor to find what the APS-C focal length will be. So for a 20mm lens:

20mm x 1.5 crop factor = 30mm APS-C focal length

blockstream – What is the difference between the two transaction headers on the Bitcoin Liquid sidechain network?

You can see transactions for this asset

For the second transaction, it has a header of

  • 802dc4c4a08fcf4f50e4320bdb5eb596afc01c95dd0ff6afb83304aeb989be15 (2020-01-07 11:21:58 UTC)

Underneath the transaction, is a another header of

  • 81efc96bea93fcb5992831d8311dec63a0b1d17072ec2e6f1263901b1bd26000 (2019-10-31 19:05:58 UTC)

What is the difference between these two? why does one transaction have two headers?

Difference between Dynamic & Static Website

Static Website looks basic and is for a smaller company,and simply delivers information without any bells and whistles, it could be a static website.
Static websites can only really be updated by someone with a knowledge of website development. Static websites are the cheapest to develop and host.

Advantage :Quick to develop, Cheap to develop, Cheap to host.

Disadvantage : Requires web development expertise to update site, Site not as useful for the user, Content can get stagnant

Dynamic website can give the website owner the ability to simply update and add new content to the site.Some examples of dynamic website features could be: content management system, e-commerce system, bulletin / discussion boards, intranet or extranet facilities, ability for clients
or users to upload documents, ability for administrators or users to create content or add information to a site (dynamic publishing).

Advantage : Much more functional website, Much easier to update, New content brings people back to the site and helps in the search engines
,Can work as a system to allow staff or users to collaborate

Disadvantage : Slower / more expensive to develop, Hosting costs a little more.


computer architecture – what is difference between speculation & prediction?

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Difference Between MVC and MVC + 3 Layered Architecture?

I haven’t been able to find a definitive answer online, so I’m hoping that someone with experience can help answer this.

Many MVC tutorials I find online end up using the MVC architectural pattern as the architecture for the entire application. But, I have read conflicting statements from those on this site and other sites who say that MVC is just an architecture for the presentation layer of a layered architecture.

At this point I’m leaning towards the idea that it is perfectly valid as a pattern for an entire application, especially because it seems like overkill to have to design 3 separate layers for a small to medium sized application.

Which is it? Is MVC a perfectly good architectural pattern for an entire application, or is it just meant to be used as the presentation layer of a layered architecture?

htaccess – What’s the difference between access and access plus in ExpiresByType directive?

These two directives are the same.

The plus keyword is entirely optional. It is just syntactic sugar, to make it (arguably) more “readable”.

As stated in the Apache docs for mod_expires:

ExpiresByType type/encoding "base(plus num type) (num type) ..."

The plus keyword is optional.

So, include it or not – it is up to you. But, as with everything, it is important to be consistent. Include it OR don’t include it; don’t mix it.


ExpiresByType image/jpg "access 1 year"

As I noted in my answer to your other question, you should probably be using image/jpeg here, not image/jpg.

Is there a difference between deleted tweets and removed tweets?

I’m trying to identify a way to determine if a tweet was deleted by the user or forcefully removed by twitter.

Is there a difference? If so, how to identify it with the twitter web app/API?

google sheets – How can I calculate the difference between two time fields, being the second greatest than the first one?

I’m having trouble getting negative hour as a result in Excel. For instance:

G           H
08:30       06:00

I would like to get a column with the difference between H and G. So I would be filled with -02:30.

When I do a simple calculation, like G2-H2, I get 22:00 as a result.

Any ideas on how to fix this?

I saw this post How to handle Negative Time Delta in Google Spreadsheets, but none of them have the solution I’m looking for.

replacement – Repeated ReplacePart On Each Element of a Square Matrix for Eigenvalue Difference

I would like to ask for some help on a deriving a command for a problem I’m trying to tackle.

So, I have a large n by n square matrix, whose elements are all either 0 or 1. I want to see by how much the single largest eigenvalue of the matrix (which Mathematica gives as the first element in the list from Eigenvalues()) changes when I change each element of the matrix individually, so that I can produce a list of this eigenvalue difference for each element. A 10 by 10 matrix would thus give a list of 100 eigenvalue differences. By “changing each element”, I mean switching the element to 1 if it’s a 0 already or to 0 if it’s a 1 already.

i.e. if the matrix is {{0,1,0},{1,0,1},{1,0,0}}, finding the largest eigenvalue of {{1,1,0},{1,0,1},{1,0,0}}, then that of {{0,0,0},{1,0,1},{1,0,0}},then that of {{0,1,1},{1,0,1},{1,0,0}} etc…

I experimented with Loops but since i and j need to increase independently I couldn’t resolve that issue. I also thought of combining ReplacePart and If but can’t find a ‘neat’ way of doing this for very large matrices.

I’d appreciate any help for the Mathematica newbie.

What the difference Between file() and fopen in PHP

What is the difference between those two functions, however they do the same thing… | Read the rest of