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8 votes
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variable K cannot be deleted

The Wolfram Language currently uses seven single letter capital letters for various core system functions: C, D, ...
Arnoud Buzing's user avatar
7 votes
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How to reset a built-in symbol to its default definition?

If the System` symbol you want to modify is a kernel function, then you can just use Clear to reset it to its default state. For your ...
Carl Woll's user avatar
  • 131k
7 votes

Items known by CurrentValue

The secrets can be revealed by examining strings in the executable file: ...
kh40tika's user avatar
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6 votes

Items known by CurrentValue

Another way to get more stuff is to just see what's available to FrontEnd`Value[FrontEnd`CurrentValue[__]] as that's how ...
b3m2a1's user avatar
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6 votes

Items known by CurrentValue

Since many people seem to be looking through files in text editors I thought I'd give a way to scrape this data automatically (it should work for any kind of expression you want, as long as it's in a ....
b3m2a1's user avatar
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6 votes

How to programmatically ask if Mathematica is running as an administrator

Here's how you can do it using IsUserAnAdmin SHELL32 function on Windows, without using NETLink: ...
Kuba hasn't forgotten Monica's user avatar
6 votes
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How to make the variables in $init.m$ not impact the autocompletion

Don't put symbols you don't want to show up in auto-completion into the Global` context. Use the same mechanism you would for a package. ...
Szabolcs's user avatar
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6 votes

Solve says my system of equations has no solution

Try Reduce ...
zhk's user avatar
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6 votes
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Catching MachineUnderflow in Version 11.3

I just want to save this information from comments. @ilian mentioned in comments: This command is simply not needed in 11.3 and later because what it accomplishes is now the default (and only) ...
6 votes
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How to build a tri-diagonal matrix

Try n = 20; M = Table[If[i == j, -(1 + 2/h^2), If[Abs[i - j] == 1, 1/h^2 + x1/(2 h), 0]], {i, 1, n}, {j, 1, n}] or also ...
Cesareo's user avatar
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5 votes

variable K cannot be deleted

K is part of the System` context. You were removing symbols from the Global` context only, ...
Szabolcs's user avatar
  • 236k
5 votes

Solving equation with multi variable matrix input

After correcting all errors and normalization to A, we have ...
Alex Trounev's user avatar
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5 votes
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how to obtain all Messages for Mathematica build-in functions?

You could do something like this: ...
Rolf Mertig's user avatar
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4 votes

Can one effectively edit a Front End Resource that is already loaded?

This is more comment than answer as you want in-memory modification, but it is possible to force the text resources to be reloaded. You do this with, e.g., ...
b3m2a1's user avatar
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4 votes
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Complete list of values for \$SystemID, \$OperatingSystem

The purpose of $OperatingSystem is to check what general OS you are on. You would check $OperaingSystem for tasks such as ...
Szabolcs's user avatar
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4 votes

How to obtain non-trivial solution?

Mathematica is correct. In general, there will only be the trivial solution. You are trying so solve an equation $ M x = b $ with $ b= 0$. This will have a nontrivial solution if and only if $\mathrm{...
Natas's user avatar
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4 votes
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How to obtain numerical solutions of a system of two equations with two unknowns?

Clear["Global`*"] EDIT: Corrected intervals in Solve ...
Bob Hanlon's user avatar
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4 votes

Where is the new System`ConvertersDump`$extensionMappings?

I haven't found extension mappings in the System context, but here's a way to build mappings of file extentions and file formats that shouldn't be affected by ...
creidhne's user avatar
  • 5,250
3 votes

Choice of variables name affects the behavior of expression evaluation

They are the same expression, just simplified differently. You can verify by changing the b->x in the first: ...
bill s's user avatar
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3 votes
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Composition of functions not working

You must use Symbolize of the built-in Notation` package to use Subscripts as symbols. Note:...
Edmund's user avatar
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3 votes

Where is the new System`ConvertersDump`$extensionMappings?

By checking the output of Export["a.txt", Export["a.txt",] // Trace] // SystemOpen I find the variable ...
xzczd's user avatar
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2 votes

Where can I permanently modify $Path?

You could modify the global options in the options editor (Win.OS**Ctr + Shif + O**). look up the EvaluatorStartup and put code ...
Jerry's user avatar
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2 votes
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One inequality with two variables

A mathematical proof would be best, but Mathematica can provide some evidence against the statement that ...
corey979's user avatar
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2 votes
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Solve says my system of equations has no solution

I think MMM is being ingenuous. Reduce returns a rather complicated expression with a lot of conditionals (24 of them). It turns out that the equation for ...
m_goldberg's user avatar
  • 108k
2 votes

Where does Mathematica get the value of Environment["PATH"] on newer version of OS X?

As noted in the second answer to the question you linked to, this is not entirely stable from version to version in OS X. That's under Apple's control, not ours. It also varies based on the ...
Itai Seggev's user avatar
  • 14.2k
2 votes

variable K cannot be deleted

If K is evaluated then click on "description of K" and you get information: K is a default generic name for a summation index in a symbolic sum. The bug is that this information is missing in the ...
granular_bastard's user avatar
2 votes
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How to put equations in Block or Module to return n values?

Don't put your definitions for other functions in your definition of w. Write your code like this: ...
m_goldberg's user avatar
  • 108k
2 votes
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Programmatically defining variables

Clear["Global`*"] It is much easier to use an indexed variable and use Format to display the variable any way that ...
Bob Hanlon's user avatar
  • 160k
1 vote

Solving a system of equations for a fraction

To solve for arbitrary groupings of values, I usually introduce dummy variables and eliminate. ...
eyorble's user avatar
  • 9,498

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