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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14
votes
5answers
403 views

How can one manually change the rule ordering

I have a function which has some general behaviour, but that should act on some specific kinds of objects in some other way. I know that Mathematica is supposed to automatically order the rules so ...
1
vote
1answer
33 views

How to unshadow a chosen definition for a function

I want to use the package NCAlgebra. However after successfully installing the package and trying to write some code, basic functions like SetNonCommutative[...] ...
1
vote
3answers
61 views

How to make a list (of data points) whose name is the same as the file name from which the data is imported [duplicate]

I have a set of files, e.g. file1.dat, file2.dat,... containing data (list of data points to plot, manipulate...) I want to do the following ...
2
votes
1answer
80 views

Clearing a global variable from inside a Module

This is a highly simplified version of a initialization problem I have with a complicated program with many (about 100) modules. If one enters: X=42; Clear[X]; the ...
2
votes
0answers
39 views

Share variables among notebooks with different Kernels

So I have a server running in another notebook with a secondary kernel. I run my main notebook and launch the server notebook, but I have configured the variables in my main one, and can't find a way ...
2
votes
0answers
56 views

Changing variables in a series expansion

I want to compute the Taylor expansion of some pure function f[x_], but then perform a change of variables in the resulting expression. So, for example, the output ...
1
vote
0answers
66 views

Binding a variable to an unbound variable [closed]

I'm trying to do something like the following: (minimal example, f2 unbound) ...
1
vote
2answers
60 views
3
votes
1answer
54 views

Setting a One Dimensional Function Equal to a Constant over a Specific Range

I am trying to take the output from NDSolve and create a variable equal to the solution except for a certain range of values. Here is the code I am trying to use ...
0
votes
1answer
58 views

How to implement the for loop to replace text strings or texts?

I wonder define a bunch variables named like $X_1$, $X_2$, $...$, $X_n$. Is there some smart way to declare them instead of by pure typing. One trick I can image is to use the for loop,...
2
votes
0answers
60 views

Follow-up to “How to differentiate formally?”: Efficiency concern

In link to "how to differentiate formally?" and particularly to the answer by @Jens, I want to do something like this: ...
1
vote
1answer
72 views

Converting the subscript of matrix name to a variable

I want to change indices of matrix name during loop for creating different matrices. For example; ...
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. ...
2
votes
1answer
43 views

Definition of a function depending on a sequence

let $a_{n}$ is a given fixed sequence, say $a_{n}:=1/n$. I would like to define something like $$D_{j}:=\sum_{k=1}^{j}\frac{1}{j!}BellY[j,k,\{a_1,a_2,\dots,a_{j-k+1}\}].$$ Function BellY is ...
2
votes
4answers
307 views

Defining a General Complex Number

I am trying to compute the Complex conjugate of two complex numbers multiplied together. However, when I go to define my complex numbers as $a+b I$ and $c+dI$ it does not like $b$ and $d$ because they ...
3
votes
2answers
91 views

Module, local variable

Lets say I define a Module, that internally use iterating in a Table or Do, say something ...
6
votes
2answers
105 views

Force evaluation of the right-hand side of a local variable definition

One can do expression = a + 1; f[a_] := Evaluate[expression] but how would one do something like this ...
0
votes
1answer
34 views

Variable Definitions and Random Numbers [closed]

I have currently created the following matrix: m={{RandomReal[{0,1}],RandomReal[{0,1}]},{RandomReal[{0,1}],RandomReal[{0,1}]}} In other words, a $2 \times 2$ ...
3
votes
2answers
105 views

Sections with unidirectionally shared variables

I have 2 sections is my notebook: ...
3
votes
2answers
69 views

How can I adjust the global input variable of a function to the value of a local variable within the function

I am trying to define a function f[l_] that will perform an operation on whatever input variable I use (normally I use l which ...
1
vote
5answers
168 views

Do not expand matrices in Mathematica calculation

Here is an example of a problem I'm having. Consider that I have defined: omega={{p[t]},{q[t]},{r[t]}} x={{a},{b},{c}} R={{1,2,3},{4,5,6},{7,8,d}} What I would ...
0
votes
1answer
99 views

Variable dependency…easy one

I'm brand new to Mathematica...should be an easy one. Instead of writing u[x] everywhere in the code, how do I assign the dependency early on like this: u=u[x] ...
3
votes
2answers
108 views

How to use locally scoped dynamic variables in Manipulate for expression and control parameters

I have a Manipulate that has dynamic variables that I want to use in the displayed expression and use in the parameters for the manipulate controls. I only ...
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 ...
0
votes
2answers
81 views

How to define $x^n$ where $x=\pm 1$ and $n\in\mathbb{Z}^{+}$?

I do not know how I can define $x^{n}$ in Mathematica, where $x=\pm 1$ and $n=1,2,3,\ldots$. For even values of $n$ we simply have that $x^{n}=1$. While for odd values of $n$ we have that $x^{n}=x$. ...
1
vote
1answer
60 views

Define operator with special characters [duplicate]

I have looked here which describes how to define operators. I was wondering whether there was a way to assign thes operators to special characters? eg Let $\odot:=(a+b)(ab),$ so ...
1
vote
3answers
173 views

How to replace element of list by index

I'd simply like to replace the value x at index [[j,i]] in a two dimensional table with the value ...
2
votes
1answer
46 views

Strange behavior when defining a symbol/function pointwise

I am well aware of the fact that floating point number have finite precision, so one needs to be careful when comparing them. Still, I find it disturbing/surprising that the following input into ...
5
votes
1answer
94 views

Naming conflicts with Dummy variables in several packages conflicts

I'm using several packages in a notebook. In each packages there is functions defined with dummy variables. When I load the several packages in my session, i've got a warning message: ...
0
votes
1answer
56 views

Setting the solutions of an equation as a variables [closed]

This is probably a simple question, but i couldn't find a solid answer. So i have an equation Solve[{F[x, y] == 0, G[x, y] == 0}, {x, y}] but i want to use the ...
1
vote
0answers
53 views

Subscripts in variable names: Bug?

In the following plot, one of the two functions {-par, par} defined by ...
0
votes
3answers
138 views

Define a matrix depending on variable in Mathematica [closed]

I am translating my code from Python to Mathematica. I am trying to define a matrix, whose values depend on a variable chosen by the user, called kappa. In Python the code looked like that: ...
2
votes
1answer
67 views

Is there a shorthand for Optional with Condition?

I have a recursive function that does some work to an object for a repeatedamount of times. ...
0
votes
1answer
70 views

Weird subscript name in output [duplicate]

One of my first times using mathematica, I'm getting a weird Subscript(1,0) output when I try to solve a derivative. What is going on and how can I fix this?
0
votes
1answer
57 views

Simplify huge output or using the output without showing it in full [closed]

I'm trying to solve a system of differential equations. It works fine but Mathematica creates a huge output, which, when shown in full, results in a file size about 100 mb. Using Simplify doesn't work ...
1
vote
1answer
140 views

Iteration convergence of Newton approximations

I am trying to determine for which initial values Newton's approximation of specific functions (EX: f(x)=x^2 -1)converge and to what numbers it will converge to. *Where Newton's approximations are ...
0
votes
1answer
143 views

Plotting Complex Numbers - Functions of Complex Numbers [duplicate]

So I have to generate a few different plots with z, where z is a complete number... z[x_, y_] := x + y*I F[z_] := (25*Pi*z*I)/(1 + 10*Pi*z*I) First, I need to ...
0
votes
1answer
57 views

Calling a function on a variable with parameters [duplicate]

I have an equation that contains parameters. I want to use it in a function like NDSolve, but I can't seem to figure out how to do so. Here's an example: I define ...
4
votes
1answer
193 views

How can I overload a function with multiple bracket-slots so f[a][b] and f[a] can coexist?

Maybe this is not even possible: I want to create a function f that can have two input brackets like: f[a_][b_:1]:= a*b and ...
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
69 views

Variables input generation for Minimization in High dimensional space [duplicate]

I'm currently doing optimization in a high dimensional space. I was thinking of giving FindMinimum (or NMinimize not certain ...
4
votes
3answers
222 views

Using Block with a list of variables

I have a list of variables var={v1,v2}; which I want to protect/localize during a particular operation. I have decided that I want to use ...
9
votes
1answer
239 views

Context of localised (dynamic) symbols

When you localise a symbol with Module, the created unique symbol is usually in the current context. There seems to be an exception to this which has further ...
11
votes
1answer
183 views

Copy Built-in function to new name

It is know that some built-in functions are system function and changing their properties may cause trouble. Suppose for example I want to change features of Cases: ...
0
votes
0answers
15 views

Use of placeholders in functions [duplicate]

I'm having some trouble with Mathematica's placeholders within functions. The function sel[lowerLimit_] should select all elements of x that are greater than the lowerLimit: ...
9
votes
2answers
342 views

Using up-values and down-values

I have a problem I'm trying hard to find a solution for, although I don't know if a solution exists. The following rules produce the result e[2].f[] ...
2
votes
0answers
25 views

Determining default value from previous arguments [duplicate]

How does one specify a default value for an argument which is dependent on the previous arguments of a function? For instance, consider the function ...
2
votes
1answer
105 views

Table of references [duplicate]

I have a list of variables (say a, b, c, d, e) that I want to assign in a single command. {a,b,c,d,e} = {1,2,3,4,5} would ...
0
votes
0answers
89 views

Numerical Integration/Function

I have a problem with a function defined numerically through an integral of the form: ...