Questions tagged [system-variables]

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50
votes
9answers
2k views

Items known by CurrentValue

CurrentValue can be used to poll the state of numerous system values such as the mouse position. Its help page doesn't list all possible items, though. An item like ...
18
votes
2answers
4k views

Where can I permanently modify $Path?

I've quite forgotten: what file does one modify in order to add directories to $Path globally? Specifically, I want to include ...
17
votes
1answer
281 views

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

A number of special definitions are loaded from .tr files on Front End initialization and are accessible via FrontEndResource. ...
15
votes
2answers
620 views

How to programmatically ask if Mathematica is running as an Administrator

To avoid execution problems in a program I need to know if Mathematica has been "Run as administrator". What would be the cleanest way to programmatically getting this information?
15
votes
1answer
400 views

Interpretation of the result of ?@

This might be a very trivial question but as a beginner, I don't know the answer. I was exploring ? and after running a cell containing ...
11
votes
4answers
311 views

How to change the variables Qi's to Ri's in one or two steps

I was wondering if there is a command in Mathematica to change all the following Qi's to Ri's? For example, change Q1 to R1, Q2 to R2, etc. ...
11
votes
2answers
394 views

Catching MachineUnderflow in Version 11.3

Ilian's answer to question 72229, involves SetSystemOptions["CatchMachineUnderflow" -> False] Evidently, this worked in earlier versions of Mathematica, but ...
10
votes
1answer
280 views

Why do DateList, DateString, and AstronomicalData ignore $TimeZone?

My reading of the documentation for DateList and DateString lead me to believe that both functions use ...
9
votes
2answers
669 views

How to obtain the computer's hard drive serial number, BIOS ID, CPU number, MAC and so on use Mathematica?

I want to packed my program use RSA algorithm. Of course, $MachineID can be used but I want to make it safer. Can Mathematica obtain the computer's hard drive ...
8
votes
2answers
616 views

How to set the timeout value for *Data functions

I haven't measured this precisely but it seems the default timeout value for retrieving EntityValues with *Data functions is in ...
6
votes
5answers
407 views

Is there an analogue of the Variables command for general expressions? [duplicate]

The command Variables[poly] gives me a list of all variables that appear in the expression poly, which involved sums, ...
6
votes
1answer
76 views

how to obtain all Messages for Mathematica build-in functions?

Help says Messages[symbol] gives all the messages assigned to a particular symbol. These are called message identifiers per help: Message names always consist of ...
5
votes
2answers
319 views

Syntax highlighting conflict

I'm trying to syntax highlight this expression: x=$\sqrt{\pi }$//N and from various sources I've learned that x (the assigned symbol) belongs to context Global while the Pi and N belongs to System. So ...
5
votes
2answers
190 views

Equivalent of __FILE__?

Many languages define a special identifier whose value is the path to the source file currently being processed. (For example, in C, this is done through the ...
5
votes
1answer
90 views

How to reset a built-in symbol to its default definition?

I'm trying to add functionality to some of Mathematica's built-in functions in a package I'm building. I'm not trying to overwrite any functionality—just add it where it isn't already defined. I ...
5
votes
1answer
275 views

Setting $RecursionLimit crashes Mathematica 10

I have encountered what I shall presume is a bug: setting $RecursionLimit repeatably crashes the Mathematica 10 kernel: ...
5
votes
3answers
348 views

One inequality with two variables

I would just like to know if this: ((a - b)/(b*Log[b])) - Log[Log[a]] + Log[Log[b]] exceeds 0 for any combination of a and <...
5
votes
1answer
231 views

Is it safe to change the value of $TimeZone?

I'd like to configure some of my notebooks to assume all calculations using dates, times and locations (notably AstronomicalData , but others too) take place at the ...
4
votes
3answers
133 views

variable K cannot be deleted

If a value is assigned to a variable that is named by capital K it cannot be deleted. This effect can be observed directly after start of the program. Is this a bug?
4
votes
2answers
782 views

Solve says my system of equations has no solution

I got a system like this (just for example): I need to get some of the variables expressed in a form like the following. x == (z - z1) Tan[α1q - μ ] + x1 Let's ...
4
votes
1answer
165 views

Mathematica not seeing my environment/system variables

I'm trying to access my environment variables in Mathematica, but I get a Failed result every time. For example: $ echo $USER jlconlin but in Mathematica I do: ...
4
votes
2answers
324 views

Creating a variable from Reduce[] output in Mathematica

Say I have the following input: Reduce[{t*c==50, t==5}] the output: t == 5. && c == 10. Is there a way to create a ...
3
votes
3answers
276 views

Accessing temporary value of a Nest evaluation

The function Nest[] must store the temporary values in the memory somewhere (those values that would form the entries of the list which is returned by the ...
3
votes
1answer
119 views

Complete list of values for \$SystemID, \$OperatingSystem

The documentation lists some "typical values", but it leaves out some; e.g. "Windows-x86-64". Also, if the main difference between the two variables is that ...
3
votes
2answers
135 views

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

Under macOS Sierra, at least, where does Mathematica (currently 11.2) get the value of Environment["PATH"]? A comment to the accepted answer at Why does ...
3
votes
1answer
656 views

Solving a large system of nonlinear equations

I have a system of 80 nonlinear equations with 64 variables to solve in Mathematica but it takes a lot of time (about two hours) and then it return "no more memory available" knowing that I have 8GB ...
3
votes
1answer
347 views

How to restrict global variables to within a given notebook? [duplicate]

Possible Duplicate: Is there a way to separate variables between multiple notebooks? I assigned a global variable like a=10; It works in all my notebooks, but ...
3
votes
0answers
191 views

Shared variables between notebooks using the same kernel not working in mathematica 10.1?

I am trying to access the variables over two Mathematica documents, this works fine when I use Mathematica 9 but when I attempt to do the same on 10.1 it doesn't work. I have set both notebooks to ...
3
votes
0answers
83 views

Where can I find detailed information about the SystemOptions?

I'm looking to optimize my Mathematica script, and I'm willing to go spelunking with low-level system options. The problem is that I've been looking in the Mathematica documentation, but there doesn'...
2
votes
3answers
2k views

Solve the system of equalities and inequalities

I have a system of expressions, in which each expression is an equality or inequality expression of the following form: Var = Var1 + Var2 Var $\odot$ number Var $\odot$ Var1 $\odot$ = $\leq | \geq | =...
2
votes
1answer
168 views

Solving equation with multi variable matrix input

Background, here are the equations that I am trying to solve: Where R, E1, E2, V1, V2, P are all user inputs. X/A goes from -2 to 2 and Z/A goes from 0 to -2. Below is the code that I have so far. ...
2
votes
2answers
63 views

How to find non-trivial of a system of equation?

I have a system of four equations ...
2
votes
1answer
415 views

strictly positive solution to $Ax=b$

How to find in mathematica one real strictly positive solution, if any, of $Ax=b$. A is rectangular matrix. Thanks
2
votes
1answer
941 views

Importing data from excel and assigning a variable to each of its columns

How should I assign variables to the data imported from excel containing 3 columns which are time, mean and standard deviation. I want to perform operations on the three variables to get new variables....
2
votes
1answer
68 views

Newbie Issues with Solving & Plotting a System of equations

I'm having some problems with my mathematica code, I think I'm overlooking something simple. I get valid solutions for u0 thru u4, but it doesnt generate any plot at all. Also, I'd really like to plot ...
2
votes
0answers
38 views

What is the purpose of the two variables Global`args and Global`dims [duplicate]

When opening the mma, I find that two variables Global`args and Global`dims have been defined. One can check them by running <...
1
vote
1answer
107 views

How to make the variables in $init.m$ not impact the autocompletion

The autocompletion is very convient in Mathematica,but it will make one annoying sometimes when you have a ton variables.I give a scene I encounter.I usually make ...
1
vote
1answer
93 views

How to obtain non-trivial solution?

I have the following system of equations. $ quad\quad\quad\quad u+\alpha v+v+e^{\frac{i \alpha }{2}} (\alpha -1) x=\alpha u+e^{-\frac{1}{2} (i \alpha )} (\alpha +1) z, +u+v=\alpha (v+w)+w+y, (\...
1
vote
1answer
3k views

How to understand and use DSolve solution

This equation is simple to DSolve in Mathematica, but I don't know how to use and understand solution. ...
1
vote
4answers
130 views

Solving a system of equations for a fraction

I want to solve a system of equations not for one specific variable but for a fraction of two variables. How can I do that? I want to solve: ...
1
vote
1answer
249 views

How to set UnitSystem permanently

I would like to set the system of units ($UnitSystem) permanently to "Metric". I know that I can do ...
1
vote
0answers
103 views

NDSolve 2 functions 2 variables with intermediate calculation : (1 time-space eq) + (1 space eq)

I have a system of differential equation with this structure : $$\left\{\begin{split}&\partial_t n(t,r) + \nabla. \big(n(t,r)v(t,r)\big)=0 \\ & f\Big(n(t,r),v(t,r),\partial_r n(t,r),\partial_r ...
1
vote
0answers
92 views

solve a non-linear system of 27 equation

I have the following system of 27 equations: ...
1
vote
1answer
672 views

How do assign an interval of values to a variable in order to use them in a function?

From my code (below) I have K1 and K2 set to zero in order to test this numerical method. However, K1 is on an interval from 0 to 32, and K2 is on an interval from 0 to 8. I would like to know if ...
0
votes
1answer
61 views

Choice of variables name affects the behavior of expression evaluation

I tried to expand this polynomials. With x, it is increasing with the right order, however with b it is in a random order. The only difference is that I change b to x and it works. ...
0
votes
1answer
233 views

Solving a differential equation for a variable in a function

This may sound like a very trivial question, but I need to solve a differential equation as follows: ...
0
votes
1answer
82 views

How to put equations in Block or Module to return n values?

i have this code it return EigenValues, it's all right. Problem: i have to specify n in order for summation and solution to give output. Solution: i just need ...
0
votes
1answer
121 views

Developing Mathematica applications with IntelliJ IDEA [duplicate]

I create Mathematica application. For example testPrj. Now I want load this application for test. Here is a problem: how can I setup environment for loading my application with simple ...
0
votes
2answers
62 views

Sum elemets of an array

I am not sure this is something that is possible to implement in mathematica, but my question is the following. I have a system three linear equation where the coefficients in front of each variable ...
0
votes
1answer
123 views

Why is N not valid as variable in ParametricPlot? [closed]

Why is ParametricPlot[{Log[N!], Log[Sqrt[2 Pi N] E^-N N^N]}, {N, 1, 10}] not working when ...