# 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.

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40 views

### Store boolean expression into a variable

My purpose is to use a boolean expression as a requirement that a pattern must comply. The requirement is c1 == "a", and I am using it to select a string from a ...
239 views

### Name a list with Table

I am struggling to find a way to assign a value from a list to names from another pre-defined list with Table[]. names = {first, second, third} ...
76 views

### Use Alphabet[] as a variable in a function

I'm trying to figure out if I can use the letters contained in Alphabet[] as variables for a function. As a simplified example, I'd like to do something like: ...
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### Variables for multiple data files plotting using same Mathematica notebook

I am not an expert in mathematica, I have this following code. As you see I import a text file under the name "MyPoint1", plot with "pAll" then I do some more calculation with more variables and ...
31 views

I am trying to create a table by iteratively calculating its values using a temporary variable accu: ...
31 views

### ReplaceAll Not Working Correctly

I'm trying to use replaceall to redefine my expression in terms of a separate variable.. ...
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### How to restrict the use of variables to the notebook? [duplicate]

I am solving two problems simultaneously in which the variable x is defined. To the left of the image, i'm solving shape functions and matrix operations. But to the right i'm solving Green's function. ...
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### Redefine function after change of coordinates (variables)

I wish to define functions of (possibly) several variables and then apply variable transformations in order to obtain a more comfortable expression. But I run into trouble because I need to redefine ...
33 views

### Extract variables from sum of unevaluted functions

I have sums of the form sum = a f[1,1,0] + b f[1,2,0] + c f[1,2,1] + ... It is always linear in f[a,b,c]. I would like a ...
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### Reversing the flow of the equation sign. Compacting an equation. Choosing which variables to show

Here's a simple example of what I'm trying to get at with that mysterious title. I start off with a Hermitian matrix that I derived analytically ...
36 views

### remove one of the column in the output of Solve command

I would like to remove one variable in the output of the "Solve" command without changing the rest. For instance, in the following code ...
83 views

### From f[g[x,t]] to f[g]

How can you change f[g[x,t],t] to f[g,t] ? I have differential equations ...
46 views

### Computing Higher Order Tensor of Variable Rank

The following code takes a vector x of variable length, computes the outer product of the vector with itself to form the matrix $\rho$ of dimension $2^n \times 2^n$....
35 views

### Functions with Variable Numbers of Arguments: Outer Vector Product

I am trying to write a function that takes a column vector of variable dimension as an input and returns the outer product matrix as an output. What I have tried: ...
455 views

### How to transform a function from f[#1] to f[x]

So I have this function : Sqrt[-1 + Tanh[#1 - #2]^2] & How can I transform it into f[x_,y_]=Sqrt[-1 + Tanh[x - y]^2] ...
493 views

### General::ivar 0 is not a valid variable when using Series in Plot

I have been having some trouble graphing a Taylor series approximation (Series). ...
88 views

### Make assumption for function with variable argument

I would like to assume that a>t[b_] for any b, such that e.g. Simplify[a>t[c]]==True. ...
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### Saving variable inside Manipulate command

I have been working in a plotter using "manipulate", I let the code below. However, I would like change between different kind of "options" that I will add them after, the problem is when I change to ...
73 views

### How to read in and assign values from a txt file?

I have a text file that I would like to import into Mathematica - after searching around the internet, I can't seem to find any pages that explain how to do this: The text file containes these four ...
66 views

### Table and FindRoot of a 2 variable function of x and t : cos(x + 3t)

I am trying implement mathematica commands: Table and FindRoot, of a 2 variable function <...
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### Problem with fitting

So I have a very simple question related to a simple topic, but also directly related to a fitting problem. I see that my question is related to this question but I don't manage to make the bridge ...
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I have ...
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### Five equations to solve 6-variables question, is it possible?

I was given a task to find the value of variable a,b,c,d,e and f. But I'm not sure it is even possible, given that only 5 equations are available. Can anybody point out how to solve these: ...
44 views

### How to use a table with two variables as the values for a function with two variables (x and y)? [duplicate]

I'm sorry if this is a dumb question. I am a student and have 0 prior experience with Mathematica or any sort of coding and I have looked at various resources trying to figure it out myself but still ...
32 views

### Bounding Solve results to named variables

How can i bound results of my Solve function to variables properly? This metod works but causes unexpected troubles i struggle to resolve ...
131 views

### How do I create a variable that uses I?

I'm planning on working with a set of non-linear differential equations. A few of the equations look like: Mathematica tells me that I is protected. Is there any ...
34 views

### Simple question about variables into functions

Im trying to write a very simple code that will solve an equation. total = 800; side1 = x; side2 = total - 2 x; f[x_] := side1*side2 f[x] f'[x] Solve[f'[x]==0] ...
26 views

### How to define a function, that generates matrix of variables, which can be later used in Reduce?

My goal is to generate matrices, on which I will put different constraints in Reduce funcion, e.g.: ...
70 views

### Separating variables in a set of equations

I have a very large set of equations eqs with variables denoted by capital letters like PVA, QA, etc. and small letters like ica[1,2], tr[2,3] etc. And I have ...
47 views

### Apply different PlotStyles to functions with functions as variable [closed]

I have a function func[expr,var] with which I want to plot the list expr[var] and have different styles applied to it. When ...
50 views

### Rearranging similar terms in an equation

In a piece of code I am writing, I run into an equation of the form ...
53 views

### How to show the answer in terms of another variable

if we have A = 1; B = 44 + 1 output :: B = 45 how we can show B like this output :: B = 44 + A
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### Possible to solve this function?

I have this function: Emax[T_, d_] := -(1/2) + d + d/(-1 + E^(d/T)) - 1/2 Coth[1/(2 T)]; All I want is to transform this Function so I get: ...
61 views

### Showing variable values on a 3D Plot

I am running a 3D plot a 100 times to show the dynamics of two undetermined variables (cM and cR) for a 100 values of ...
26 views

### Extract and name PNG's from loops [duplicate]

I want to extract PNG files and name them depending on the dummy variable of a loop. For example, starting from ...
38 views

### Use Solve for two Functions to find 1 common Variable

I have 2 functions that look like this: F[t_,d_]:= 10+t+2d G[t_,d_]:= 5+t+d I'd like to solve this in such a way to know for which t both Function have the Same value. I assume that this won't be ...