Questions tagged [system-variables]

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6
votes
1answer
71 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 ...
0
votes
0answers
42 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 $...
4
votes
3answers
125 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?
2
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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 <...
0
votes
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
vote
0answers
101 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),\...
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 ...
5
votes
1answer
87 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 ...
0
votes
0answers
79 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
votes
1answer
164 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
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. ...
11
votes
2answers
372 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 ...
0
votes
1answer
180 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 ...
1
vote
4answers
127 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
votes
0answers
164 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
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 ...
3
votes
2answers
127 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 ...
-9
votes
1answer
121 views
4
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2answers
770 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
118 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
vote
0answers
92 views

solve a non-linear system of 27 equation

I have the following system of 27 equations: ...
5
votes
3answers
342 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
votes
1answer
115 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 ...
17
votes
1answer
276 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
vote
1answer
106 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
247 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
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 ...
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 ...
9
votes
2answers
663 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
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 ...
8
votes
2answers
603 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 ...
15
votes
2answers
614 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
votes
0answers
82 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
votes
1answer
162 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
votes
2answers
234 views

Module function corrupts string? [closed]

I have the module who should replace some elements of a matrix with checkboxes ...
2
votes
1answer
405 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
votes
1answer
651 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 ...
4
votes
2answers
320 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 ...
0
votes
1answer
120 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
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
2answers
318 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 ...
2
votes
1answer
938 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....
1
vote
1answer
665 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
0answers
131 views

Block, With, Module, can anyone help me understand the distinction? [duplicate]

I've been working heavily with Block[] for months in my research so I've read the documentation for the seemingly similar commands With[], Block[], and Module[]. Personally, I've had by far the ...
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 | =...
3
votes
3answers
273 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 ...
6
votes
5answers
399 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, ...
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 ...
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: ...
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. ...