Questions tagged [system-variables]
The system-variables tag has no usage guidance.
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Where is the new System`ConvertersDump`$extensionMappings?
I used to find the extensions mapping from System`ConvertersDump`$extensionMappings, which gives a mapping like "{"*.3ds" -> "3DS"...}&...
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Identifying the parameter that flips the solution
I have solved a system of ODEs numerically. As the plot shows, the solution SolJx is positive for the parameters I have chosen. However, if you decrease (more ...
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Plot of phase portrait of system of 4D non linear differential equations
While numerically solving ths system of differential equations:
...
- 23.2k
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1
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Plot phase portrait of a system of ODE
I have the following system of 4 differential equations:
...
- 2,154
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Replacing System` definitions in a context whilst still maintaing acces to them [duplicate]
Given the system operator TensorContract I can define a new one, TensorContractLazy with the attribute ...
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1
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How to permanently modify the $Path in Mathematica [duplicate]
I was trying to add permanently a path inside $Path.
"/Users/Softwares/HEP_Softwares/MT-1.0"
Following $Path manual I did the following
...
- 1,552
2
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1
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Composition of functions not working [closed]
I am trying to set a function within a function. What I do is to first create a function with two arguments. Then I would like to set a new function with the same two arguments, in which the previous ...
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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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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 ...
- 325
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How is it possible that $SystemMemory is set to zero?
For one of my Windows machines (Mathematica 12.x.x, only one of them) apparently $SystemMemory returns 0 (zero). I'm unable to do anything with that, since ...
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How to obtain numerical solutions of a system of two equations with two unknowns?
I have two equations with two unknowns $-10<x<0$ and $0<y<15$
$$3 y \cosh (4 x) \cos (y)+(2 x+5) \cosh (x) \sin (y)=0,\\3 x \cosh (x) \cos (y)-(2 x+5) \sinh (x) \cos (y)=0$$
I would like ...
- 149k
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Square root problem
Consider the following code
NDSolveValue[{
x'[t] == x[t]^a,
x[0] == 0
}, x, {t, 0, 10}]
which solves the equation $x'(t)=x(t)^a$, for some exponent $a$, with ...
- 233k
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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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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:
<...
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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)...
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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, (\...
CommunityBot
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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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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?
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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 $...
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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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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 <...
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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}...
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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),\partial_r ...
CommunityBot
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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 ...
- 23.2k
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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 ...
- 65.3k
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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 ...
- 2,399
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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.
...
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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 ...
CommunityBot
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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:
...
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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 ...
- 47k
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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 ...
- 123k
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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 can I find the collision time of 2 ellipsoids that rotate with infinite speed? [closed]
I have 2 ellipsoids:
...
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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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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 ...
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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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5
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3
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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 <...
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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
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- 233k
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How to set UnitSystem permanently
I would like to set the system of units ($UnitSystem) permanently to "Metric".
I know that I can do
...
CommunityBot
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1
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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 ...
CommunityBot
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1
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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 ...
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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 ...
- 123k
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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 ...
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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 ...
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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 ...
- 63