# 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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### how to define an example of ODE that represents an undamped forced oscillator whose time evolution is described by beats

I am a newbie in Mathematica and I really don't know how to define an example of ODE that represents an undamped forced oscillator
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### Changing the dependent variable

I'm using NDSolve to solve a set of ordinary differential equations. The output is something like. ...
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### No Solution For Solve with Free Variable [duplicate]

Mathematica returns no solutions for this simple query: Solve[a*x == x && x != 0, {x}] (* output: {} *) Clearly, when a ...
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### How to asign well numerical values efficiently before to plot?

A problem is presented when the substitution of the numerical values for this function ...
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### Issue with calling one notebook from inside another one

I am calling one notebook (N2) from inside another notebook (N1). The results are transferred correctly from the second notebook to the first one. But when I try to compare the results from the two ...
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### How to Append the value of a variable and not the variable itself

So lets say I have a = Some complicated code that changes list = {} AppendTo[list, a] Obviously it would give me ...
62 views

### Using an if statement to assign a value to a variable

New Mathematica user here. I'm using some code from a colleague and editing it to give me more specific results in finding the zeros of a complex polynomial. I am attempting to find a way to assign a ...
57 views

### Better way for constant expressions in functions than storing as global variables?

For example, I wrote a function like this: inversions[list_] := Complement[ Subsets[{1, 2, 3, 8, 4, 7, 6, 5}, {2}], Subsets[list, {2}] ] But as you see, ...
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### Assign variable array as function input and generate slider inputs for Manipulate

New to Mathematica. I want to be able to input some parameters, do some calculations, and end up with some output in a functional form such as: ...
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### 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: ...
466 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] ...
616 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). ...
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### 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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### 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 ...
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### 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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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: ...
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### 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 ...