# Questions tagged [system-variables]

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### 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 ...
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### 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),\...
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### 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 ...
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 ...
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### 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 ...
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### 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. ...
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### 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. ...
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 ...
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### 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 $Path manual I did the following ... 4answers 127 views ### Solving a system of equations for a fraction I want to solve a system of equations not for one specific variable but for a fraction of two variables. How can I do that? I want to solve: ... 0answers 164 views ### How can I globally change$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? ...
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### 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 ...
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### 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 ...
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### How can I find the collision time of 2 ellipsoids that rotate with infinite speed? [closed]

I have 2 ellipsoids: ...
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### 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 ...
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### 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 ...
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### solve a non-linear system of 27 equation

I have the following system of 27 equations: ...
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### 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 <...
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 ...
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. ...
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### 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 ...
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### 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 ...
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 ...
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?
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### 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'...
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### 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: ...
234 views

### Module function corrupts string? [closed]

I have the module who should replace some elements of a matrix with checkboxes ...
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
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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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....
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### 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 ...
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### 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 ...
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### 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 | =...
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### 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 ...
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### 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, ...
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 ...