Questions tagged [variable]
Questions on the use or manipulation of Mathematica variables (i.e. names associated with a changeable value). Use [variable-definitions] or [assignment] for questions on variable context localization, or assignment.
331
questions
0
votes
0
answers
40
views
Identify a condition among variables that satisfy an inequality
I have a symbolic function that produces the output
a = (1 - e - mu/n) Log[(1 - e - mu/n)/(1 - mu/n)] + (e + mu/n) Log[((e + mu/n) n)/mu]
If I substitute ...
- 376
0
votes
1
answer
63
views
A specific usage of "Solve" function [duplicate]
It is something from Simplifying polynomials with conditions on variables, that intend to minimize the number of variables.
The problem is the usage of ``Solve". I know how to solve equations, ...
- 115
0
votes
0
answers
44
views
how to use subscripted variable such as a_i as the control of Manipulate?
I'd like to define a series of variables called $l_1$,$l_2$, etc., in Mathematica, using the "ctrl+_" shortcut. Moreover, I want to use these variables as the controls of a Manipulate[] ...
- 695
1
vote
1
answer
76
views
How can I define a function with a variable with subscript?
I want to define a function in Mathematica:
$$h(\tau_x)=\tau_x$$
$\tau_x$ has no special meaning. To be honest, it's totally OK if I use the function $h(x)=x$ to replace $h(\tau_x)=\tau_x$. It doesn't ...
- 13
1
vote
2
answers
97
views
Generate family of linear inequalities from vector variable for use in `FindInstance`
Suppose that I have a vector variable xvec = Array[x, 10].
How do I generate the family of linear inequalities
$$F = \{ {x\in\mathbb{R}^{10}:x_1\geq x_2,\ldots,x_9\...
- 125
0
votes
1
answer
25
views
sum elements (variables) of a vector variable [closed]
I would like to sum elements of a vector variable, e.g.,
Is
xvec = Array[x, 10]
s24 = Sum[xvec[i], {i, 2, 4}]
where $s_{24}:=\sum_{i=2}^4 x_i$.
However, I am ...
- 125
0
votes
0
answers
38
views
Invalid Variable Error for Solve When Using Law of Cosines
I'm making a shadow simulator, and am using the Law of Cosines to calculate a certain angle in a triangle with two known widths and one known angle. I'm using Solve ...
2
votes
1
answer
60
views
Problem with integration with indexed variable
I wonder why I can not have a correct integration form on Mathematica with some indexed variables.
Indeed, when I write :
...
- 23
0
votes
3
answers
114
views
Conflicting variables
So, I read a set of variables and respective values from a file and store them in a variable
specs = {{"Type", "KP", "fp"}, {"LP1", 2, 2000}, {"Type", ...
2
votes
5
answers
238
views
Repeating definitons of variables
I have the piece of definitions
y = 1;
x = 2;
n = 2;
a := (y^(x - 1) + n)/(y^(x - 1) + y^(x - 2))
I want to keep defining y as a by doing:
...
- 162
0
votes
0
answers
64
views
Answer changes slightly when re-run
I am trying to resolve why I get slightly different answers when I re-run my notebook. Here is my full code:
...
- 1
1
vote
3
answers
76
views
Local variables in a module don't show their actual values
I need to do the following transformation that
pick[a,b] -> ex[c|->{c[a],c[b]}]
ex is a function that accepts a function as parameter which returns a list ...
- 307
7
votes
1
answer
179
views
How to Obtain Complete List of Properties
I am working with Matrix Market matrices in Mathematica (specifically GEMAT12), and I saw from other posts that you call properties of a variable exemplified below:
...
- 105
0
votes
0
answers
69
views
Can you dynamically create variable names in Mathematica? [duplicate]
I was wondering if there is a way of Mathematica to read a string or number and create variable with that name.
For instance imagine that I have a file with the word data1. I would want to create a ...
2
votes
0
answers
72
views
how to understand the locality of variables in Mathematica
(in the first i should say may be the title is not very accurate)
how to understand case like the following:
...
- 343
2
votes
0
answers
69
views
a basic question about variable in Mathematica
I can't describe exactly the problem I'm experiencing, but this kind of problem has a remarkable feature, that is, commands which couldn't work in the before can be executed correctly when i turn off ...
- 343
3
votes
1
answer
278
views
Does Mathematica have that function which returns the variables back [duplicate]
Does Mathematica have this function where I can give a system of equations as an input and the function return back to me the variables which were included in that system. For example:
input Function[...
- 51
3
votes
1
answer
189
views
How to use <* *> in tex to substitute mathematica variables [closed]
I am generating tex files with a "for" loop in Mathematica. In each file I need to have different quantities. So I am defining a variable in Mathematica, which is is evaluated during each ...
- 133
0
votes
0
answers
53
views
SolveAlways with functions as fixed variables
I have an expression that looks like this:
c1*dot[p[1],p[2]]+c2*dot[eps[1],p[2]]+c3*dot[p[1],S,p[2]]+...==dot[p[1],p[2]]+...
i.e. an equation where in the left ...
- 239
1
vote
0
answers
83
views
Internal variable in Sum inside a function [closed]
I am writing a simple function which performs a sum, but run into an unexpected answer.
...
- 479
3
votes
4
answers
432
views
Define a delayed function depending on a global variable as though the variable's contents was pasted
Problem
Say I previously defined a variable (maybe through some extensive calculation)
thing = (a+x)y
Then, I want to use that expression elsewhere. In general, I ...
- 751
5
votes
1
answer
214
views
Is it necessary to use Print inside a Block? [closed]
If I use a Block with variables already used and ask it to Solve an equation inside the Block...
- 319
0
votes
0
answers
21
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 ...
- 862
0
votes
0
answers
45
views
Reusing local variables through Reduce and ToRules
Problem: I am interested in solving a system of linear equations through Mathematica. In my current test scenario, I am having trouble using the Reduce function followed by the ToRules command. I ...
- 111
1
vote
0
answers
33
views
How to best query if an expression contains Symbol/variable
Say I have this expression, among many:
...
- 181
1
vote
0
answers
79
views
Why =. is not clearing the value of a variable in this case? [closed]
I am reading "Mathematics and Algorithms" as part of the Wolfram Tutorial series.
In "Values for symbols" section of the "Algebraic Calculations" chapter it is described ...
- 323
0
votes
1
answer
49
views
Function of two variables - how to supress one variable dependency
I have this equation i would like to solve:
e0 = (2 \[Alpha]1g)/((1 - v1g) (c^2 - b^2))
Integrate[r \[Tau]1[r, t], {r, b, c}] - (2 v1)/E1 A1;
Function e0 ...
- 97
0
votes
0
answers
67
views
How to define variables properly in mathematica, a variable with two name [duplicate]
I wanted to define a variable in the name "beam_frequency", this is quite possible in other programming languages like python and Matlab. How to define two pair variable name in Mathematica ...
- 417
2
votes
2
answers
336
views
Would it be poor advice to assign roman numerals as top variables?
For example like so.
x = 10;
xi = 11;
xv = 15;
Is there an automated way to spit these numbers out maybe 1-1000.
- 7,565
2
votes
2
answers
100
views
Rewriting an expression while using another parameter
I wish to rewrite V and M with the given A. I have provided what the end result is supposed to look like.
Here is V
...
- 121
0
votes
0
answers
41
views
Scaling a variable multiplied by power series is not giving expected output
I have a power series getting multiplied by a variable, which gets scaled by the small parameter used in the power series. As an example, in the following dummy series:
...
2
votes
2
answers
100
views
How to plot the perimeter of an ellipse where the variable is its eccentricity?
I'm basically just trying to plot a function where the x value is the eccentricity of an ellipse and the y value its perimeter.
I've tried first defining the eccentricity
...
- 21
0
votes
1
answer
82
views
How to define prefix that can turn numeric?
I put these prefix in my init.m file. First I Unprotect all these symbols, set values and then
...
- 2,678
1
vote
1
answer
147
views
5
votes
5
answers
883
views
List of letters longer than the alphabet
I would like to create a list of the first $n$ letters of the english alphabet. Importantly, I would like that in case $n$ is bigger than the size of the alphabet, the letters will start repeating in ...
- 191
0
votes
1
answer
178
views
How to convert mathematica root expression to readable one? [duplicate]
I am trying to find out at what regions a function is monotonically decreasing. The function is a function of X and has two more variables epsilon and B with the constrains 0 < B, 0 <epsilon< ...
- 35
0
votes
0
answers
78
views
Cannot Optimize where NSolve and NDSolveValue are involved with Multi-Variables
My Objective Function is Sqrt[Sum[((sol[[j]])^2), {j, 1, noofnode}]/noofnode] with variables v1, v2, v3, v4, v5, v6. But just ...
0
votes
1
answer
116
views
How to change the values of a parameter within the domain in NDSolveValue?
In the following code, e is constant within the domain. But I want to change the value of e continuously within the domain. For ...
0
votes
0
answers
125
views
How to Optimize a Finite Element Model with Multiple Variables in Mathematica?
Urgent Help, Please !!!
I am attaching my codes for a Finite Element Model which needs to be optimized and the Objective Function ("of" in the code) has been mentioned at the last line of ...
0
votes
0
answers
498
views
Help with Error: Recursion depth of 1024 exceeded during evaluation
I am quite new to Mathematica. Please excuse my mistakes. I would appreciate if you could help me with the following set of commands.
...
- 1
0
votes
0
answers
41
views
how to delete a variable programmatically in a notebook from another notebook
how to delete a variable programmatically in a notebook from another notebook?
c = b;
I have already tried Remove[c] but ...
2
votes
1
answer
43
views
Arrange an expression based on variables' names
I have a problem of arranging an expression as shown in the following picture. The first expression exp is derived from other functions and equations. I want to get ...
- 663
3
votes
1
answer
124
views
Partial derivatives in a variable name
I would like to create variable with names of the form \[PartialD]g and \[PartialD]\[PartialD]g. Is there any way to do this?
- 2,985
1
vote
0
answers
84
views
Full Information Maximum Likelihood - Under some other name in Mathematica
I have recently stumbled upon something called FIML - Full Information Maximum Likelihood. Apparently this methodology helps overcome missing variables provided the gaps are random. Searching the ...
- 790
5
votes
1
answer
149
views
What Does this Syntax Mean in Ouput from DSolve?
When I run the code
DSolve[y*D[f[x, y, z], z] - z*D[f[x, y, z], y] == 0,
f[x, y, z], {x, y, z}]
I get the following output.
I don't understand this syntax. I ...
- 1,597
0
votes
2
answers
75
views
Integrate of simple equation but is not solving!
I have this simple integral but I don't know why Mathematica can't solve it?!
FullSimplify[Integrate[x/(-x^2 + a x + b)^(1/2), {x, Sqrt[b], Sqrt[R^2 + b]},Assumptions -> {a > 0, b > 0}]]
- 143
3
votes
2
answers
179
views
Making a list of variables
Consider the following code, which give a Manipulate object that returns the "total" of a certain variable var 1
...
- 4,187
2
votes
0
answers
70
views
Extracting variables [closed]
Similar to this perhaps, but I prefer a built-in function.
I have defined the expression L = a*b*c.
Is there a Mathematica function that can identify and extract ...
- 21
2
votes
1
answer
556
views
How to replace the arguments of a function?
I have the following type of (very long) expression:
$$\ldots + X[1,2,3,5] + X[2,4,5,6] + \ldots \tag{1}$$
where $X[a,b,c,d]$ is some undefined function. I would like to replace all the occurrences of ...
- 681
2
votes
1
answer
153
views
Coloring all the variables with the same name with the same color
I would like to know if there is a possibility to automatically color the variables with the same name with the same color. For example, like in the picture below:
Right now I need to do it manually ...
