Questions tagged [system-variables]

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1answer
41 views

Programmatically defining variables

I seems as though what I am interested in is unconventional, but I am interested in defining a number of different variables programmatically. For example I can write a matrix of variables by doing: <...
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0answers
44 views

Solving a multivariate polynomial system takes too long

I have tried to solve this system ...
0
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0answers
34 views

Is there a way to automatically store the output of a command to a variable directly?

Generally I do a computation then I have to manually take that number and make it equal to another variable which I define which I can then use to do subsequent computations. Something like this: <...
1
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1answer
91 views

How to build a tri-diagonal matrix [closed]

I have an algorithm that works for a Tri-Diagonal matrix in Mathematica, but I need a good way to build my starter matrix A. It's a 20 variable system (and will be a 200 variable system once I get it)...
1
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1answer
203 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, (\...
6
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1answer
84 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 ...
4
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3answers
161 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?
0
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0answers
44 views

Set of multivarible expressions to be re-expressed a single variable

I have a set of expression such as $\frac{3x+y-z}{6x}$ and $\frac{3 x-y+z}{12 x}$, which can easily get re-expressed as $p$ and $(1-p)/2$, where $p=\frac{3x+y-z}{6x}$, but is there a way to find this $...
11
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2answers
434 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 ...
2
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0answers
46 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 <...
0
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0answers
29 views

Differential equations system's solutions differ when one of the constant is 0

I am solving the following system of equations with Mathematica. $u'=-k_{1}ux+k_{2}x^2, x'=k_{1}ux-k_{2}x^2$ and I obtain the solution for x: $x(t)=\frac{e^{k_{1}C_{1}(t+C_{2})}k_{1}C_{1}}{-1+e^{k_{1}...
1
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0answers
107 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 ...
0
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1answer
83 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 ...
5
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1answer
110 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 ...
20
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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 ...
0
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0answers
95 views

Minimize and Table of variables

I use a list of variables to Minimize a particular quantity { Q, val1, Table[Pi, {i, 1, m, 1}} where i is the subscript of P. However in this way I have ...
2
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1answer
205 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. ...
0
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1answer
62 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
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1answer
232 views

How to permanently modify the $Path in Mathematica [duplicate]

I was trying to add permanently a path inside $Path. "/Users/gkdgoutam/Softwares/HEP_Softwares/MT-1.0" Following $Path manual I did the following ...
5
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2answers
193 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 ...
1
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4answers
188 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: ...
0
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0answers
204 views

How can I globally change $Path permanently? [duplicate]

I have two packages that I would like to append to $Path. I have looked at this link for help but after I quit Mathematica, I have to repeat the process again. Where can I permanently modify $Path? ...
0
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2answers
65 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 ...
4
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2answers
154 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 ...
17
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1answer
289 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. ...
1
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1answer
111 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 ...
50
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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 ...
4
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2answers
859 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 ...
3
votes
1answer
121 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 ...
1
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0answers
92 views

solve a non-linear system of 27 equation

I have the following system of 27 equations: ...
5
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3answers
376 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 <...
0
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1answer
165 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 ...
3
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1answer
275 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 ...
15
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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 ...
2
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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 ...
9
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2answers
736 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 ...
3
votes
0answers
204 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 ...
5
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1answer
232 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 ...
8
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2answers
677 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 ...
4
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2answers
341 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 ...
15
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2answers
631 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?
3
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0answers
84 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'...
4
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1answer
170 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: ...
-7
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2answers
239 views

Module function corrupts string? [closed]

I have the module who should replace some elements of a matrix with checkboxes ...
2
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1answer
429 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
3
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1answer
696 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 ...
0
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1answer
122 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 ...
5
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1answer
279 views

Setting $RecursionLimit crashes Mathematica 10

I have encountered what I shall presume is a bug: setting $RecursionLimit repeatably crashes the Mathematica 10 kernel: ...
6
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5answers
416 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, ...