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.
3
votes
0answers
44 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]
...
4
votes
3answers
277 views
How to Clear variables with apostrophe?
An apostrophe ' is often used when we want to distinguish two variables. For example, if we already have a variable t and we may ...
10
votes
1answer
177 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
5
votes
1answer
67 views
Why doesn't DumpSave work for elements created within a local notebook context?
I recently noticed that when dealing with notebooks with local context, I cannot successfully DumpSave variables, or, rather, when I call ...
3
votes
2answers
202 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
117 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
67 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
112 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
140 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
97 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
73 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
...
27
votes
3answers
647 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 ...
0
votes
1answer
72 views
Riffle not acting as expected [closed]
I have defined two tables:
R = Table[Subscript[\[ScriptCapitalR], -i], {i, -12, -1}]
T = Table[Subscript[\[ScriptCapitalT], -i, -i - 1], {i, -12, -1}]
I want to ...
3
votes
2answers
123 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 ...
5
votes
1answer
97 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. ...
4
votes
1answer
109 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
25 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
...
11
votes
7answers
482 views
How to Set parts of indexed lists?
I would like to assign a list to an indexed variable and then change it using Part and Set like this:
...
3
votes
1answer
87 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
63 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
89 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....
14
votes
3answers
397 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 $dR$ for a function $R(a,b,c)\,$ and ...
2
votes
2answers
265 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 ?
12
votes
6answers
333 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 ...
7
votes
3answers
376 views
Elegant manipulation of the variables list
I have a list of global variables (some of them are indexed variables), for example:
varsH = Hold[U0[1], U0[2], B0, V0[1], V0[2]]
Or (if it is easier to handle) ...
1
vote
2answers
130 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
237 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
144 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
124 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
260 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
159 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 ...
9
votes
4answers
357 views
how to differentiate formally?
I have been wrapping my head around this for a while now and I have not found a solution so far.
I want to work with an arbitrary number of variables in mathematica and use some built in functions.
...
2
votes
0answers
76 views
Evaluating a function on permutations of its arguments
Say I have a function "temp" of $n+1$ variables, $y,z1,z2,z3,...,zn$. I want to test if my function has certain symmetries like swapping $y$ with square of any $z$, swapping any two of the zs, ...
5
votes
1answer
89 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
214 views
How to create functions of arbitrary number of variables?
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 $z_2$?
...
3
votes
1answer
117 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
60 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
189 views
local variable naming & symbolic argument
I'm stuck here with my variable assignment in this scenario
...
0
votes
3answers
138 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 ...
1
vote
0answers
67 views
Context “Unique to This Notebook” makes variables black even if they're not defined?
I'm trying to use this technique to keep variables separated between different notebooks. It seems to be working fine, except that variables turn black as soon as they are evaluated — any ideas why ...
3
votes
0answers
58 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 ...
15
votes
5answers
3k views
How do I clear all user defined symbols?
Is there some way to do this other than going to Evaluation -> Quit kernel and firing a new one up?
12
votes
1answer
143 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:
...
30
votes
3answers
666 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
313 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 ...
2
votes
1answer
183 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
458 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)
...
1
vote
0answers
271 views
Using constraints in Solve[]
I'm not sure if the title fits.
I'm basically just looking for a way to define a value and constrain it to $[a,b]$ when I use Solve later.
More specifically, I ...
10
votes
4answers
247 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
152 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 ...
