linear algebra – Matrix of the derivative operation $D$ with different basis

Suppose $V={p(x) : p(x) text{ is a polynomial so that its degree is less or equal to 2}}$ and $W={p(x) : p(x) text{ is a polynomial so that its degree is less or equal to 1}}$ are two vector spaces. If $D: V to W$ is a linear transformation given by $D(p(x))=p'(x)$ (the derivative). Find the matrix D related to the bases as stated in: $$D_{{1,x,x^2}}^{{1,x}}$$

My proposal for the matrix is begin{equation*}
A =
0 & 1 & 0 \
0 & 0 & 2

for which I define it as a two row, because of the matrix multiplication as the outcome will have two rows too, also that $D(x^k)=kx^{k-1} $. Nevertheless, I am not a hundred percent sure this matrix works or if there is another argument that I still have to show so that this proof is complete, because when proving the general case with the standard basis for polynomials, the same base is used. Link to what I am refering to in the last line: Derivative matrix for n-th degree polynomial

ag.algebraic geometry – Operation on algebraic stack

Let $X$ be a smooth algebraic stack and $D$ be a normal crossing divisor. Let $pi: tilde{D}rightarrow D$ be the normalization of $D$. Let $sigma: tilde{D}rightarrow tilde{D}$ be an involution. It is easy to see that $sigma$ induces an equivalence relation $R$ on $X$. Consider the quotient $frac{X}{R}$ of $X$ by the equivalence relation $R$. Is $frac{X}{R}$ an algebraic stack?

This question is a generalisation of Artin’s theorem on algebraic spaces. The statement is true in the category of Algebraic spaces.

google cloud platform – ERROR: ( Error Response: [13] Flex operation

PLS HELP!!! I already checked all the quotas and they seem to be fine. Don’t know what cause the error?

Updating service (default) (this may take several minutes)…failed.

ERROR: ( Error Response: (13) Flex operation projects/objreg-278609/regions/us-central1/operations/214e2dcc-8a7a-4204-898a-580dc14e6a97 error (INTERNAL): An internal error occurred while processing task /appengine-flex-v1/insert_flex_deployment/flex_create_resources>2020-05-28T10:58:17.771Z15266.ow.8: Deployment Manager operation objreg-278609/operation-1590663498298-5a6b334c5f340-589a82aa-ed20dd6f errors: (code: “RESOURCE_ERROR”
location: “/deployments/aef-default-20200528t054325/resources/aef-default-20200528t054325”
message: “{“ResourceType”:”compute.beta.regionAutoscaler”,”ResourceErrorCode”:”403″,”ResourceErrorMessage”:{“code”:403,”errors”:({“domain”:”usageLimits”,”message”:”Exceeded limit ‘QUOTA_FOR_INSTANCES’ on resource ‘aef-default-20200528t054325’. Limit: 8.0″,”reason”:”limitExceeded”}),”message”:”Exceeded limit ‘QUOTA_FOR_INSTANCES’ on resource ‘aef-default-20200528t054325’. Limit: 8.0″,”statusMessage”:”Forbidden”,”requestPath”:””,”httpMethod”:”POST”}}”

design – Inject an Operation ID across multiple application layers

I am playing with my simple personal project – a simple REST API application and I am currently struggling with a kind of design problem.

The problem:

How to insert an operation ID (request ID, an identifier of each operation) into each “layer”?


Let’s say I have a UserRepository trait (interface) with 2 implementations (say, InMemory and Database), which is used by multiple services (say, CreateUserService, UpdateUserService). All these services are then used by a facade, let’s say the UserFacade. This facade is called by the CLI tool or the Users REST handler.
What I would like to be able to do is to create a unique Operation ID for each “operation” (request or a CLI call). This ID would be used for logging across the whole application, I would like to be able to access it in the repositories, services and facade. Later I would like to access the logs and trace how the request was processed by each of the layers.

Possible solutions that come to my mind are:

  • Pass this operation ID to each method as an additional parameter. I
    consider this ugly since the interface would be polluted by the extra parameter, unrelated to the business logic.

  • Create a whole structure of facades and services using the operation ID (the ID will be provided to each instance via the constructor for each request or CLI
    action). I like this approach but I think this would be performance/memory heavy because it would need to create a lot of objects for each processed request.

  • Some “global state” (thread-local…) storing the operation ID?

I am trying to not specify any concrete language since I consider this a general problem, more related to the design than the used language or technology.

dataset – In Wolfram Mathematica, who do I query the result of a Counts operation efficiently and conveniently?


Say, I’m given a dataset, like the one below:

titanic = ExampleData({"Dataset", "Titanic"}); titanic

Answering with:

Sample of the Titanic example data

And I want to count the occurrences of any combination between { "1st", "2nd"} and {"female", "male"}, using the Counts operator on the dataset, like:

genderclasscounts = titanic(All, {"class", "sex"})(Counts)

Gender Class combination counts

Problem statement

This is not a “flat” dataset and I don’t have a clue how to query in the usual way, like:

genderclasscount(Select( ... ), ...)

The resulting dataset doesn’t provide “column” names to be used as parameters in the Select nor can I refer to the number representing the count by a name.

And I’ve no clue how to express an Association as a value in a Select!?

Furthermore, try genderclasscount(Print), this demonstrates the values presented to the operation over this dataset are just numbers!

An unsatisfactory attempt

Of course, I can “flatten” the Counts result, by doing something horrific and inefficient like:

temp = Dataset((row (Function) 
     AssociationThread({"class", "sex", "count"} -> row)) /@ (Nest(
      Normal, genderclasscounts, 3) /. 
     Rule({Rule("class", class_), Rule("sex", sex_)}, 
       count_) -> {class, sex, count}))

Flattened Counts over a dataset result

In this form it is easy to query a count result:

First@temp(Select(#class == "1st" (And) #sex == "female" &), "count")


So, my questions are

  1. How can I query the (immediate) result of the Count operation in a convenient and efficient fashion, like using a Select operation on the resulting dataset? Or, if that is not possible;

  2. Is there an efficient and convenient transformation of the Counts result dataset possible facilitating such a query? With “convenient” I mean, for example, that you just provide the dataset and the transformation handles the rest. So, not something like I’ve shown above in my unsatisfactory “solution” πŸ˜‰

Thanks for reading this far and I’m looking forward to anwsers and inspiration.


software installation – How to install .run and .bin files in raspberry pi 3 b+ with Rasbian operation system?

I’m very beginner in raspberry pi so I don’t know how to install .run and .bin files on Rasbian or other operating systems like Xubuntu and Lubuntu.
I used these command to install:
“sudo apt install” or “sudo apt-get install”
“” is my downloaded file to install.
But the result of those commands is:

Reading package lists… Done
Building dependency tree
Reading state information… Done
E: Unable to locate package ‘
E: Couldn’t find any package by glob ‘’
E: Couldn’t find any package by regex ‘’

Also I used these command too:
First “sudo chmod +x” and then “./”
The result is:
“bash: ./ cannot execute binary file: Exec format error”

Please help me.

csom – Is there an operation that changes the GUID of a SharePoint list to another value?

I have a CSOM application that I can use to access SharePoint lists.

I have edited a list https://mysharepoint.shareoint.local/sites/sc123/MyList with a GUID: 263FE49C-7FB3-4247-93CD-4AAB9770EF97

A few days later, the same list suddenly has a different GUID 7F1BA68C-8D94-48D7-BF97-AC5C6FF0665A.

I'm tracking list changes using the Change API, but I'm unlikely to be handling this particular event.

Are there operations where SharePoint lists can occur that change the GUID of a list?

What would be the Change API event that would cause this?

sqlite – sqlite3 vacuum interrupted, any other operation can no longer work

I ran vacuum over a 1TB database, since it took about 20 hours and is not ready yet, I tried to interrupt it by ctrl + c, it didn't work, so I canceled the process. Then I tried to query the database. It was only executed without result, even if I type .table or .databaseit comes out with nothing. What should I do to make the database work again? Thanks a lot

env: linux, sqlite3.7

Floating point – rounding operation result in IEEE 754

Is there a way for operations with single precision values ​​in IEEE 754 (float, 32bit) to somehow condition the two operands to ensure that the operation result is rounded down if an accurate result is not possible?


  • Typical result (using "On the next round"): 1.0f / 3.0f = 0.3333333432674407958984375f
  • Expected result (with & # 39; rounding & # 39;): 1.0f / 3.0f = 0.333333313465118408203125f

As additional information I would do this in C99 and (unfortunately) it is not possible to configure the FPU.

mysql – Switch to Docker and illegal mix of collations (latin1_danish_ci, IMPLICIT) and (latin1_swedish_ci, IMPLICIT) for operation & # 39; = & # 39; Error received

I'm trying to change our application from a server to a docker on a virtual machine. We use MySQL for data and Tomcat (spring) for the GUI. It seems to work well in Docker and is executed when a stored procedure is called. There is an error message:

Request processing failed; nested exception is java.lang.RuntimeException: java.sql.SQLException: Illegal mix of collations (latin1_danish_ci,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation '='

This error message does not occur if the application is running on the server (not on the Docker version). So I'm assuming there is a configuration that I couldn't transfer from the original application to the Docker-based application. Since it works with the same data on the server, I don't think it should be necessary to change the tables or the procedure.

The Docker creates a MySQL: 5 container and a Tomcat: 8 Contaner and communicates via a Docker network. The GUI connects to the database via this line:


I only have & # 39; localhost & # 39; in & # 39; db & # 39; changed because Tomcat and MySQL are in separate containers in the Docker version. I've tried some variations of character encoding like latin2, but without luck.

I searched the configuration files in / etc / mysql / but found nothing that seemed relevant.

Does anyone know which settings I was missing or what else I can do to further describe the problem? I am new to the industry and am learning while working on this transfer in Bouth Docker and MySQL.