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Formal solution to large system of equations using Reduce

I'm trying to solve a large system of equations (there are 12 equations with 12 complex variables, hence I'm expecting to be able to write 12 real components as functions of the remaining). I tried to ...
Fredrigo6's user avatar
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0 answers
17 views

Is it possible to find a closed-form expression for determinant of the $k+1$-dimensional three-diagonal matrix whose entries obey particular rules?

I have this $k+1$ dimensional three-diagonal matrix in which $k=0,1,2,3,...$. I want to compute its determinant. Of course, for each fixed $k$ it is easy to compute the determinant. My question. Since ...
charmin's user avatar
  • 1,159
0 votes
1 answer
112 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 ...
EeeE's user avatar
  • 1
5 votes
2 answers
70 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"...}&...
RoderickLee's user avatar
0 votes
0 answers
47 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 ...
NC520's user avatar
  • 479
1 vote
1 answer
153 views

Plot of phase portrait of system of 4D non linear differential equations

While numerically solving ths system of differential equations: ...
Syn1110's user avatar
  • 51
0 votes
1 answer
79 views

Plot phase portrait of a system of ODE

I have the following system of 4 differential equations: ...
Syn1110's user avatar
  • 51
0 votes
0 answers
22 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 ...
user3257842's user avatar
2 votes
1 answer
100 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 ...
Rubén Pérez Sanz's user avatar
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0 answers
66 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 ...
Andrzej Odrzywolek's user avatar
1 vote
1 answer
117 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 ...
user avatar
4 votes
1 answer
213 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 ...
sam wolfe's user avatar
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1 vote
1 answer
126 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: <...
Steven Sagona's user avatar
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0 answers
69 views

Solving a multivariate polynomial system takes too long

I have tried to solve this system ...
GaSa's user avatar
  • 101
0 votes
0 answers
37 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: <...
UppedSolution77's user avatar
1 vote
1 answer
296 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)...
Bogus's user avatar
  • 25
1 vote
1 answer
1k 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, (\...
user avatar
6 votes
1 answer
220 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 ...
Nasser's user avatar
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0 answers
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 $...
11Elves's user avatar
4 votes
3 answers
443 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?
granular_bastard's user avatar
2 votes
0 answers
52 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 <...
user69086's user avatar
0 votes
0 answers
41 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}...
Ксения Цочева's user avatar
1 vote
0 answers
221 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 ...
J.A's user avatar
  • 1,265
0 votes
1 answer
96 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 ...
user avatar
5 votes
1 answer
269 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 ...
thorimur's user avatar
  • 9,020
0 votes
0 answers
151 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 ...
E. Kelly's user avatar
2 votes
1 answer
293 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. ...
Alc's user avatar
  • 41
0 votes
1 answer
69 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. ...
shixx597_Min's user avatar
12 votes
2 answers
652 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 ...
bbgodfrey's user avatar
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0 votes
1 answer
570 views

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 ...
BabaYaga's user avatar
  • 1,888
1 vote
4 answers
311 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: ...
jopi's user avatar
  • 15
0 votes
0 answers
268 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? ...
cave's user avatar
  • 1
0 votes
2 answers
102 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 ...
rob's user avatar
  • 87
5 votes
2 answers
463 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 ...
murray's user avatar
  • 11.9k
-9 votes
1 answer
173 views

How can I find the collision time of 2 ellipsoids that rotate with infinite speed? [closed]

I have 2 ellipsoids: ...
gy ab's user avatar
  • 35
4 votes
2 answers
1k 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 ...
crx's user avatar
  • 87
4 votes
1 answer
181 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 ...
user avatar
1 vote
0 answers
103 views

solve a non-linear system of 27 equation

I have the following system of 27 equations: ...
C. Basile's user avatar
5 votes
3 answers
524 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 <...
user3141592's user avatar
0 votes
1 answer
576 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 ...
Vidya Sagar V's user avatar
17 votes
1 answer
359 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. ...
Mr.Wizard's user avatar
  • 272k
1 vote
1 answer
132 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 ...
yode's user avatar
  • 26.8k
5 votes
1 answer
362 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 ...
rhermans's user avatar
  • 36.7k
15 votes
1 answer
417 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 ...
MathX's user avatar
  • 1,709
2 votes
1 answer
70 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 ...
funkyhunky's user avatar
9 votes
2 answers
960 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 ...
zzy's user avatar
  • 319
3 votes
0 answers
269 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 ...
Kevan's user avatar
  • 31
9 votes
2 answers
929 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 ...
shrx's user avatar
  • 7,817
17 votes
3 answers
727 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?
Ariel Sepulveda's user avatar
3 votes
0 answers
92 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'...
jvriesem's user avatar
  • 417