Questions tagged [system-variables]
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70 questions
3
votes
1
answer
88
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Unexpected changes of $InputFileName after using SetDirectory
I have stumbled upon a very strange interaction of the system variable $InputFileName when using SetDirectory and ...
0
votes
1
answer
163
views
Solving a system of 8 nonlinear equations
I'm new on Mathematica and have been trying to solve the following system of 8 equations with 7 variable:
However, Mathematica takes too much time trying to solve the system. I left Mathematica ...
- 1
5
votes
2
answers
121
views
Where is the new System`ConvertersDump`$extensionMappings?
I used to find the extensions mapping from System`ConvertersDump`$extensionMappings, which gives a mapping like "{"*.3ds" -> "3DS"...}&...
- 283
0
votes
0
answers
79
views
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 ...
- 479
1
vote
1
answer
244
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Plot of phase portrait of system of 4D non linear differential equations
While numerically solving ths system of differential equations:
...
- 51
0
votes
1
answer
121
views
Plot phase portrait of a system of ODE
I have the following system of 4 differential equations:
...
- 51
0
votes
0
answers
25
views
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 ...
- 904
2
votes
1
answer
140
views
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 ...
- 125
0
votes
0
answers
100
views
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 ...
1
vote
1
answer
168
views
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 ...
user80187
4
votes
1
answer
304
views
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 ...
- 5,023
1
vote
1
answer
250
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:
<...
- 1,066
0
votes
0
answers
112
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0
votes
0
answers
60
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
vote
1
answer
412
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)...
- 25