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## UBUNTU 20.04 LTS. Can’t run updates. Says version unsupported

I did the upgrade to 20.04 about 4 months ago. I downloaded it from the page that kept sending me upgrade messages, and did a fresh install on my new SSD. All worked well, updating software multiple times in the past few months from South African servers. I am now in North Africa. I tried […]

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## Allow reserved key words as methods in CPython

It looks like Python has a list of reserved key words that cannot be used as method names. For instance, class A: def finally(self): return 0 returns a SyntaxError: invalid syntax. There is a way around it with getattr/setattr, class A: pass setattr(A, ‘finally’, lambda self: 0) a = A() print(getattr(a, "finally")()) works fine. However, […]

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## How to install Keras ad Tensorflow in R?

I’m trying to install keras and tensorflow packages in R, but everytime I do this I experience problems and difficulties and,finally, fail. First, I do: install.packages ("keras") I get: `Installing package into ‘C:/Users/user/Documents/R/win-library/4.0’ (as ‘lib’ is unspecified) trying URL ‘https://cran.rstudio.com/bin/windows/contrib/4.0/keras_2.3.0.0.zip’ Content type ‘application/zip’ length 2488234 bytes (2.4 MB) downloaded 2.4 MB package ‘keras’ successfully unpacked […]

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## How to merge 2 tables based on values

Let say, I have 2 tables – Table 1 : +——+——+——+——+ | Col1 | Col2 | Col3 | Col4 | +——+——+——+——+ | 2 | A | 10 | X | | 3 | B | 23 | Y | | 2 | C | 11 | X | | 5 | D | 34 | […]

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## when zookeeper shutdown,zkDb invoke the method fastForwardDataBase(), this method add transactions from the committed log into memory

i have a question about this,e.g.,there are five node in a cluster, if leader crash and not send a commit order,and only one follower receive the proposal and sync to disk,finally,this proposal is success or fail ? /** * Fast forward the database adding transactions from the committed log into memory. * @return the last […]

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## Grasping the concept of Electronic Spin, Effective Spin and Fictitious Spin

Trying to learn alone some aspects of quantum mechanics is, sometimes, a struggle. Reading the excellent paper by Piwowarska (DOI 10.1007/s00723-018-1080-4) I was hoping to, finally, understand what is the origin of the so-called “fictitious spin $1/2$” in a $\mathrm d^7$ cobalt ion. If my cobalt is high spin ($3/2$ is the electronic spin $S$), […]

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## Grasping the concept of Electronic Spin, Effective Spin and Fictitious Spin

Trying to learn alone some aspects of quantum mechanics is, sometimes, a struggle. Reading the excellent paper by Piwowarska (DOI 10.1007/s00723-018-1080-4) I was hoping to, finally, understand what is the origin of the so-called “fictitious spin $1/2$” in a $\mathrm d^7$ cobalt ion. If my cobalt is high spin ($3/2$ is the electronic spin $S$), […]

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