Questions on assigning and unassigning definitions to names that represent them, including issues raised by context and localization. Use tag [assignment] for issues relating to Set versus SetDelayed.

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1
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0answers
185 views

Variable scope in nested NMaximize, NMaxValue

I'm trying to use NMaxValue inside other statements (FindRoot and NMinimize). Those statements should bind variable names, but I'm getting weird warnings which seem to indicate that the variables ...
7
votes
1answer
166 views

Specifying optional arguments with variables

Perhaps this is poor programming on my part, but I would like to create a function that uses a variable as an optional parameter: var = 2; f[a_:var] := {a} The ...
3
votes
3answers
208 views

Renaming a list with name obtained interactively

I have a list say: m = {1, 2, 3} The list is inside a package, and is the result of a calculation. I want to give the user the option to rename it, for example ...
1
vote
3answers
443 views

Adding subscripts to variables

I know I can define vars = Map[Subscript[x, #1] &, {"tem", "pressure", "hum", "lat", "alt", "space", "corner"}] and ...
5
votes
1answer
384 views

Proper use of arbitrary number of variables

So, I'm working on a project where the number of independent variables is not fixed. Consider a problem of $N$ independent variables, $\boldsymbol{r}$. I want to perform different things with them. ...
9
votes
1answer
135 views
18
votes
3answers
768 views

Create an adaptive amount of local variables for error propagation

I intend to write a function which calculates the result and the error for any formula with any amount of variables using the Gauß Error Propagation. The error $\mathrm{d}R$ for a function $R(a,b,c)$ ...
8
votes
2answers
247 views

Distribute and analyze large datasets

I need to analyze very large datasets, and they obviously don't fit in a computer memory. I need to produce some statistics on these datasets, and this brings me here: How can I make some statistical ...
8
votes
1answer
161 views

Different behaviours of Default Argument

I don't really understand the behaviour of Default Argument. If I execute this command in Mathematica: In: {f[a], f[a + b]} /. f[x_ + y_.] -> p[x, y] ...
18
votes
1answer
1k views

What is $ sign in Mathematica?

Is it a special sign or it can be used as anything else? For creating variables for example. $x=4
3
votes
2answers
252 views

Mathematica does not understand (R^3)^(1/3) is the same as R [closed]

In the output from a calculation in mathematica stands a/((R^3*c)^(1/3)), with c and a ...
4
votes
4answers
159 views

Put local variables for Block in a variable [duplicate]

Is is possible to assign {x = 2, y = 3, z = 4} to a variable var so that one can write ...
1
vote
1answer
351 views

Generating a list of symbolic coefficients [duplicate]

I am trying to do something which I assume should be very simple: I want to generate a list with symbolic coefficients that looks like this: ...
0
votes
4answers
1k views

Specify a variable as an integer

I have a formula that always evaluates to a certain number for any variable X under one condition that X is an integer and ...
2
votes
3answers
188 views

How to make a defined symbol stay in symbol form?

How to make a defined symbol stay in symbol form? w = 3; g = 4; {w, g}[[2]] 3 I want the output to be ...
3
votes
1answer
196 views

How to replace variables in an expression?

I have generated a matrix using Mathematica, $\left( \begin{array}{ccc} \text{cos$\theta $} & -\text{sin$\theta $} & \text{cos$\theta $}\, \text{dx}+\text{dx}-\text{dy}\, \text{sin$\theta $} ...
4
votes
2answers
94 views

Creating functions from output of other calculations

Apologies in advance if the title is vague, I'm not really sure what to call this. I have a function (call it 'foo') that generates a largeish polynomial, and it is natural to make the variables be ...
33
votes
3answers
1k views

Is there an equivalent of MATLAB's Workspace window in Mathematica?

For example, in MATLAB, a panel is available where one can see straightaway which variables are used and their dimension sizes. Is such a feature available in Mathematica? I really find it hard to ...
3
votes
2answers
778 views

Save variables values and definition

I used to do a lot of programming in R and recently switched to Mathematica. One thing that bothers me is that I haven't found a way to save variables, their values and definition! Let's look at an ...
6
votes
1answer
2k views

Module with “local functions”

I am trying to use a Module having "local functions", i.e., those which I need to define only inside this module. So I tried this: ...
0
votes
0answers
33 views

How to define a vector of arbitary length [duplicate]

I need to use a vector of length which I can change, indexed symbolically So for e.g. when N=3 I'd like to have vec={c1,c2,c3} when N=5 ...
3
votes
1answer
110 views

Is it safe to assign a variable and function of the same name for different things?

I'm writing out a notebook that goes through the van der Waals Equation of State for gases, and I run into a situation where I want to assign (simplified) Tc[b_]:=5b, use that to solve for b in terms ...
2
votes
1answer
116 views

Strange behaviour of variables in Table

I'm trying to work with some vectors and have run into a strange problem. An obvious way to define a difference of two vectors would be dif[x_,y_] := x-y I ...
5
votes
1answer
147 views

Proper localization of variable names

In functions like NonlinearModelFit I need to specify parameters with a symbol name. If I localize these parameters they get cluttered in the output (e.g....
2
votes
2answers
1k views

Global variable initialization in packages

Is it a good idea to Initialize variables globally inside a package ? will they be local by default to that package ?
15
votes
6answers
1k views

How to clear all variables except one?

I have a lot of variables: $a,b,c,d, \ldots $ I want to clear the values of all of them except $b$. It's really lengthy to write Clear[a]; Clear[c]; ... Is ...
1
vote
2answers
161 views

Why does Evaluate[a[[1]]]=0 assign a value to a variable while a[[1]]=0 doesn't?

I'm trying to do a small page counter with Mathematica, for leting me know about my reading progress on some books. I'm stuck on a problem: ...
2
votes
2answers
779 views

defining recursively a function with multiple if conditions

I am trying to recursively define a function which satisfies the following system of equations and which depends on two parameters $n$ and $l$, $$ \begin{align} A(x, n, l) &= F[ A(x,n-1,l) ]\\ ...
2
votes
3answers
219 views

how can I generate a sequence of assignments?

I want to make a sequence like follows r[1]= r[2]= r[3]= r[4]= .... r[n]= The above r[i] represents coordinates which I have ...
0
votes
2answers
142 views

How can I assign some part of data from one list to another list?

I don't know this is correct question or not,but I have a doubt. I have two Lists names are list1 and ...
4
votes
2answers
1k views

How to create a Table of Tables with indexed variables

I want to use concise code to generate a table of values that list the addition of a set of vectors. What I am looking for is essentially a Table of Tables. I will show here the kind of lists I want, ...
6
votes
2answers
213 views

Can I redefine a list as a set of variables?

Suppose I have a list mydata = {3, 14, 15, 92, 65} and in some cases I want to manipulate it as a list, like for reading from and writing to a file, or for ...
5
votes
1answer
169 views

Reloading package after accidental Remove[] of symbol

I was using Needs["PlotLegends"] By chance I removed ShowLegend by Remove[ShowLegend] How do ...
1
vote
3answers
2k views

How to create functions of arbitrary number of variables? [duplicate]

In the following code what would be the simplest way to generalize it to say some $N_f$ number of $z$ instead of just $z_1$ and $z_2$? ...
5
votes
1answer
456 views

Using external variable as a variable inside WhenEvent & NDSolve

I'm trying to use the new WhenEvent functionality of NDSolve in Mathematica 9, in order to perform an action when a variable in the system reaches a certain value. I would like this variable to come ...
0
votes
0answers
68 views

What's the best practice for nested local constants? [duplicate]

Possible Duplicate: How to avoid nested With[]? I have many situations where I have a constant that is local to a function, with other constants that are computed from it. I see that I can ...
2
votes
2answers
331 views

local variable naming & symbolic argument

I'm stuck here with my variable assignment in this scenario ...
2
votes
3answers
1k views

Better solution than returning a list of 3 values?

I have a function (using SetDelayed) that currently returns 3 values in a list. Later on I use the result of this list along with ...
3
votes
0answers
86 views

What's reliable way of finding declared but undefined functions/symbols in several interrelated packages?

I have many packages some of which use some of others. I have many symbols defined in them. Is there a reliable way of finding declared/exported but undefined functions/symbols in several ...
13
votes
1answer
314 views

Is it possible to Clear all variables (but not functions)?

I have written a Mathematica script in which I define functions and variables. Here is a vastly simplified example: ...
35
votes
3answers
1k views

Why modules with no variables?

I was reading some code, in particular, recipe 4.13 on unification pattern-matching in Sal Mangano's Mathematica Cookbook, and there were many instances of Modules with no variables in them, such as ...
8
votes
3answers
671 views

Variable variable names

I have two variables, $ u \in \{0,40\}$ and $\gamma \in \{0,1\}$. I take $10$ values of $u$ and $5$ values of $\gamma$ and using their combinations as a pair of input parameters, I perform some ...
3
votes
1answer
323 views

Can I create a dynamic number of rows in TabView through an iteration?

I have written code, with the help of stackoverflow of course, and I want to make it user friendly so that other people in my lab can use it. I'm playing with DialogCreate and similar functions. I ...
2
votes
1answer
2k views

Constructing variable names from a string

I have groups of descriptive variable names and dont want to write explicit code for each group, e.g. (and this is a contrived simplification) ...
10
votes
4answers
508 views

How to use pattern matching to assign values to Subscript[f,x_]?

I want to define two subscripted functions Subscript[f,1] and Subscript[f,2]. To keep the assignments local, I would like to ...
1
vote
1answer
581 views

How do I use a matrix that has a variable?

I seem to be getting an error whenever I try running this piece of code. Matrix12[n_] := {{1, 0}, {0, {\[Kappa]1[n]}/{\[Kappa]2[n]}}} I've already defined the ...
1
vote
1answer
380 views

How to substitute variables in interpolated function?

I'm looking for the way to substitute variables in interpolated function again to original one. (I want to know how to get P(r, theta) from Psol(v, w).) The original variables : ...
10
votes
3answers
367 views

How can I hold UpValues but evaluate other expressions?

Consider these definitions: own = "OwnValue"; down[_] = "DownValue"; sub[_][_] = "SubValue"; N[n] = 3.14; _[___, up, ___] ^= "UpValue"; The attribute ...
3
votes
1answer
218 views

How to restrict global variables to within a given notebook? [duplicate]

Possible Duplicate: Is there a way to separate variables between multiple notebooks? I assigned a global variable like a=10; It works in all my ...
2
votes
1answer
4k views

setting a variable equal to the output of FindRoot

So I set a function f[x] f[x_] := x*E^(-x) - 0.16064 Then I set a variable 'actualroot' to the function FindRoot, starting at 3 ...