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.

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0
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1answer
35 views

Where is the erroneous assignment that is causing my 'List of equations expected instead of tru' error?

I'm getting one those annoying 'NDSolve::deqn: List of equations is expected instead of True' errors. I have done everything I can think of to Remove and Clear all variables, including restarting ...
6
votes
2answers
134 views

Ignore some values at return

Is there Mathematica analogue of Python _ (underscore) or Matlab ~, a special variable, that can be used when a function returns ...
2
votes
2answers
82 views

PasteButton: Pasting expression name without quotation marks?

I am struggling to find a way to use PasteButton to paste the name of an expression (in particular a list) without showing the contents of the expression or without ...
4
votes
1answer
107 views

How to re-assign values to a List of variables?

The accepted Answer to this similar Question can only be used one time, so it's not suitable for my problem. I do high-dimensional calculations for which I need to make lists of variables, like so: ...
2
votes
2answers
61 views

How can I use an InputField value as a variable name to save to?

I'm trying to save some settings and results from Manipulate, and I want to be able to save them to different variable names. The code I have is something like ...
1
vote
0answers
65 views

Binding a variable to an unbound variable [closed]

I'm trying to do something like the following: (minimal example, f2 unbound) ...
2
votes
2answers
73 views

How to use the variables from Table in calculation

New to the site and Mathematica. I'm trying to use the finite element method to get a temperature profile. So if $q_0=f(T_0,T_1)$, $q_n=f(T_{n-1},T_n)$ and we also know that ...
1
vote
1answer
49 views

Create a list of variables of a function

How can I create a list of variables of simple functions with arguments? These functions will be defined by the user, to be manipulated with some code later. ...
1
vote
0answers
29 views

How to list all user-defined variables with current values? [duplicate]

How to get a list of all user-defined variables and those current values in the current .nb? Maybe it's a (too) simple question, sorry if so, but the answer would help me a lot in debugging some ...
1
vote
1answer
203 views

Duplicate Mathematica functionality in Mathematica clone or lisp [closed]

What is the easiest way to accomplish the following in a Mathematica clone or in any version of Lisp? Also it doesn't appear in any lisps have a similar replace function. ...
4
votes
1answer
163 views

How to make Mathematica express an equation in terms of previously defined functions

I was given a problem for my physics class, and perhaps I have taken it too far, but I wish to finish what I started. I have a function (i warn you that this does not look pretty) ...
0
votes
1answer
56 views

Global variables [closed]

I have a workbook I am writing, there are 2 cells in it and then each cell is divided into sub cells. At the top of the first cell i made a bunch of variable assignments such as length=10, x=6, d=4, ...
2
votes
1answer
72 views

Assiging random values to an array of variables [closed]

I want to create a number of variables and assign random values to them. This is possible in Python using a single line of command. To be more specific say I want to create 10 variables whose value ...
0
votes
1answer
54 views

How to give more importance to a variable in a chart

I have two variables, x and y. x goes from 0 to 10, 10 being best. ...
1
vote
0answers
39 views

How to avoid import evaluation until if wil return true

My goal is to import a data from url that depends of 1 parameter, this initialy value is null or undifined en yo have to selec some popup and then the variable has value, what is the method to do ...
1
vote
1answer
115 views

Adding letters and numbers to create a variable name [duplicate]

Let's say I have several variables, named R1, R2 and R3. I wanted to have a function ...
2
votes
0answers
51 views

Defining a function which takes lists as it arguments and threads over them [closed]

I want to define a function with lists as variables, which has the form like m = Table[2, {i, 5}]; f[x_, y_] = m*x + x*y; x and y are list variables; m is a ...
2
votes
1answer
68 views

How to choose variables of specific form

I am trying to work on a problem with a probability distribution. I wanted to get the result in analytical form. Suppose I need to keep p1, p2, p3, p4 variables such that p1+p2+p3+p4=1; How to use ...
2
votes
1answer
96 views

Is it possible to find the size of a variable in a notebook?

I have a fairly large a list of matrices matsLst, which takes about 15 minutes to compute (but computes successfully each time). I can test in the notebook that ...
1
vote
1answer
208 views

How to use Table to assign values to variables in a list?

I'm trying to do the following: R = {a, b, c, d, e, f, g, h, i}; Table[R[[n]] = RandomInteger[{0, 20}], {n, 1, Length[R]}] My intention is to assign a random ...
0
votes
0answers
38 views

Symbol-handling, force-replace instanced variables within functions! [duplicate]

Currently I am stuck with the issue of renaming an instanced variable like r1$23314 to a global one. This issue arises as I need to use a "localizeAll" Module in ...
0
votes
0answers
41 views

Is the letter “s” special in Mathematica? [duplicate]

I'm finding that the two versions of the expression below evaluate differently: ...
0
votes
0answers
48 views

Need help with notations [duplicate]

I can't create a custom variable with notation. Where is my problem? I have a big computation and I need to convert it to LaTeX. ...
2
votes
0answers
81 views

Plotting data with four variables; two labels for one of the axes

I am having difficulty related to 3D plotting task. I have a set of data points in the following form : ...
1
vote
1answer
90 views

Printing names of indexed variables instead of values

I'd like to display only the variable (indexed variable) name (in symbol form, not in string form) instead of its value in Mathematica. Say I have a variable foo[i] ...
2
votes
2answers
81 views

Can i change AutoStyles colors for undefined variables?

I want to change from blue to red the color of the undefined variables; but only for the current Notebook
0
votes
1answer
63 views

Can I name a variable as D(1,0,+1/2)? [closed]

I am trying to use variables with names as D(0,0,0), D(1,1/2,+1/2), etc. but I don't know how to do it.
1
vote
1answer
74 views

Is it possible to assign a value where the target is itself a variable

If I have a variable x := "a". Is there a way I can use it to assign a value to a, by just referring to ...
0
votes
1answer
83 views

Change of variables—Galilean transformation

I have a function of two variables, f[x, y], and I wish to do a Galilean transformation, i.e., y = z - v t, where ...
0
votes
1answer
92 views

How to specify the domain of a variable?

How can I specify for every expression the domain of a variable without using assumptions everytime i have to simplify it?
1
vote
1answer
79 views

How to make strong assumptions?

Or put in another way, how to make a variable behave as it belongs to a specific domain, even outside the use of simplify or other commands alike? For example: ...
0
votes
1answer
78 views

Variable change

If I have the following Hamiltonian: ...
1
vote
2answers
79 views

Solutions to multivariate equation

Is there any way to get Mathematica to give a set of solutions (pairs of x and y that are integers) to an equation with multiple variables? Something like: ...
1
vote
1answer
72 views

Problem using variable loaded from TextField

I'm trying to make a simple app, which loads some data via TextFields and then does something with that, but ... ...
1
vote
1answer
84 views

How can I plot a 3D graph that shows how a histogram varies with a particular parameter?

How can I plot a 3D graph that shows how a histogram varies with a particular parameter? A simple example of this would be plotting a histogram of data described by a gaussian. The gaussian is of ...
0
votes
0answers
139 views

How to assign equation solutions to variables [duplicate]

I have 12x12 Matrix with which I have to solve the equation below: ...
1
vote
2answers
109 views

Summing over n variables [duplicate]

I am currently trying to create a function taht will sum over n variables, but I don't really know how ot implement it. It should look like this: $f[n]=\left(\frac{1}{6}\right)^n \sum _{x_1=1}^6\sum ...
2
votes
1answer
128 views

Equivalent command to the Maple indets command

This carries on the discussion here and here. I had mistaken Variable[] to give you ALL variables in an expression, but apparently, it is not meant for that. ...
7
votes
1answer
891 views

Get expression type?

Is there a built in function that distinguishes between different kinds of variables? I mean something like: ...
1
vote
1answer
494 views

Explanation for coloring of variables by code editor?

I was working on some homework just now, and I realized that some of my variables have different colors, and I am not sure why. In the example below f is black, ...
0
votes
1answer
108 views

Get all variables in an expression with Variables[]

"\[Phi]" <> "1"; Variables[%] Exp["\[Phi]" <> "1"]; Variables[%] Exp[Subscript[\[Phi], 1]]; Variables[%] Say I have lots of variables used for ...
7
votes
2answers
353 views

Display variable name instead of value

Is there a way to display the variable name instead of its value? for example, I need something likevarname = 1; function[varname]; and the output is ...
1
vote
2answers
351 views

Pass the list of variables into function to change their values

I'm new to Mathematica, so I don't really know, how do what I want, and I don't even know how to google it. Doing one Mathematica task for my supervisor, I faced the following problem. I need to ...
1
vote
2answers
104 views

why the variable scope is not local when using evaluate to plot multicurve?

I noticed a surprising problem when using evaluate to plot multicurve, "evaluate" function actually consider global variable first, not the local! I can illustrate the problem using the following ...
1
vote
0answers
48 views

Settings to disable global scope

I am building a fairly large application in Mathematica, and globally scoped variables are causing issues. I would like globally scoped variables to be out-of-scope for my expressions, except by ...
0
votes
1answer
103 views

Why do For[] loop variables in different functions interfere?

I had something along the lines of: ...
1
vote
1answer
192 views

Assign values to variable names in lists

I hope somebody can help me in this (I guess) simple question: I have a list of variable names ls={w0,w1,w2} and another list of values ...
2
votes
2answers
90 views

Pattern evaluation in nested function call

I'll put the question right here, but will add some context below in case someone wonders why the heck I'm trying to do this. Why is it that I have to do two passes to get the value of the arguments ...
0
votes
2answers
2k views

How to pass a list as function argument?

I have the following function lFreqPhylo[a_, Q_, b_, p_] := Sum[Log[freqFunction[r[[p]][[i]], L[[p]][[i]], a, Q, b, {i, 1, nbranches[[p]]}]; The objects L, r ...
0
votes
1answer
37 views

How to output local variables when error message is generated without interrupting evaluation?

I am running a calculation to generate a dataset. I use several iterations to sweep over a parameter space. A few times an error message is generated (which is not the problem per se). Is it possible ...