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.

learn more… | top users | synonyms

1
vote
1answer
104 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
3answers
185 views

Declare local variable when defining a function to mimic Table[]

The problem: I want to define a function tab to replace the long line Table[f[i,j,k,l],{i,3},{j,3},{k,3},{l,3}] by a shorter ...
1
vote
2answers
349 views

TabView: Reset some dynamic variable on tab selection

Given a TabView panel like this one TabView[{ DynamicModule[{x = False}, {Checkbox[Dynamic[x]], Dynamic[x]}], "foo"}] I ...
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 $z_2$? ...
1
vote
1answer
81 views

`Quit` vs `ClearAll[“Global`*”]`

Quit erases all the definitions (by quitting the kernel), but so does ClearAll["Global`*"] (or other contexts). What's the ...
1
vote
1answer
67 views

How to extract all necessarily code for a function?

Many times when someone pastes a piece of code into SE there are missing values and symbols that the user left out. To prevent this I'm looking for a function that uproots other functions (extract ...
1
vote
2answers
177 views

Add a letter to a variable name from a list

Basically I am searching for a way to add the letter u to an existing list of variables {a,b,c,d} to obtain the variable list <...
1
vote
1answer
47 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
2answers
68 views
1
vote
1answer
72 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
83 views

Store matched variables

Edit: I am matching and replacing a particular expression. At the same time... I want to store matched variables for later use. I got it to work with messed up code involving ...
1
vote
1answer
234 views

Solving equations with QuantityVariable

I'm trying to understand how to easily solve equations that use QuantityVariable. Why does this fail? ...
1
vote
1answer
539 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: ...
1
vote
1answer
56 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. ...
1
vote
2answers
248 views
1
vote
1answer
95 views

Circumventing the default scoping: Assign a variable inside a function [duplicate]

I'm currently trying very hard to assign a variable inside a function. Therefore I'm using a function like this, which should reassign a predefined variable. ...
1
vote
1answer
371 views

Print indexed (by subscript) variable name systematically

I have some variables : Subscript[S, 1], Subscript[S, 2]...etc. But they are defined in a for loop like For[g = 1, g < 4, g++, Subscript[S, g] = g]; Later, I ...
1
vote
1answer
874 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
431 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 : ...
1
vote
1answer
152 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 x[...
1
vote
1answer
74 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 yet)...
1
vote
1answer
94 views

How to form a variable from matrix elements

I have matrix with n rows and 2 columns, say m = {{x11, y12}, {x21, y22}, ..., {xn1, yn2}. Now, I want to form three new variables for example: ...
1
vote
2answers
82 views

Calling variables with use of numbers in their names

I have got few huge matrices named by ascending numbers, e.g. x1, x2, x3,... and I need to do the same operation with all of them - to multiply their components, ...
1
vote
1answer
57 views

How to set the values into some variables from different lists [duplicate]

I have a list of Values and a list of variables. I want to set the Values into Variables. Assume the following code: ...
1
vote
2answers
224 views

setting real parameters in Hamiltonian matrix

The following Matrix represents my Hamiltonian. m = {{ B/2 - d - j/2 + a, (Sqrt[2]*j)/2, M}, {(Sqrt[2]*j)/2, B/2 + a, 0}, {M, 0, (-3*B)/2 - d + j/2 + a} How can ...
1
vote
1answer
255 views

Is linear interpolation applicable here

From my understanding about Linear Interpolation especially of that of Newton's Divided Difference Polynomial, we could get the value of F(x) from the given set of ...
1
vote
1answer
406 views
1
vote
0answers
33 views

How to define a variable describing several options? [duplicate]

Plot[y=x, {x, -1, 1}, PlotPoints -> 24, MaxRecursion -> 0, ColorFunctionScaling -> False, BoundaryStyle -> None, MaxRecursion -> 0] I will ...
1
vote
0answers
68 views

Binding a variable to an unbound variable [closed]

I'm trying to do something like the following: (minimal example, f2 unbound) ...
1
vote
1answer
163 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 ...
1
vote
0answers
61 views

Subscripts in variable names: Bug?

In the following plot, one of the two functions {-par, par} defined by ...
1
vote
0answers
120 views

How to create a complex variable from dated list values

Can anyone help me to construct a variable "PI" from values of variable x. Variable x represents a group of two time series rj and ri on equal dates(joined two dated lists with states).Variable x have ...
1
vote
0answers
348 views

specifying a list (vector) of arbitrary length

When trying to do symbolic calculations in mathematica involving a space of dimension n, which is arbitrary but fixed, I'd often like to work with vectors that have ...
1
vote
0answers
77 views

Coupled ODEs with boundary conditions - DSolve Error [closed]

I'm relatively new to mathematica and I can't find the error here. I suspect it has something to do with the fact that vx, vy, vz aren't blue on my mathematica - as in, they already have some assigned ...
1
vote
0answers
61 views

Telling mathematica that something is an integer [duplicate]

Is it possible for me to tell mathematica something is an integer? like if I typed Sin[n Pi]+Cos[n Pi] it would tell me it equals 1 for even n and -1 for odd n? ...
1
vote
0answers
3k views

How to assign (and retrieve) variables with subscripts? [duplicate]

I like to give subscripts to my variable names when the variables are related. I.e., Subscript[r, i] = 3 3 A problem arises when I later assign ...
1
vote
0answers
221 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 ...
0
votes
4answers
2k 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 ...
0
votes
2answers
120 views

Variable Value as Range

Thank you for the help so far! I would like to assign +/i signs for the function and solution such as (+)(+)(-) and therefore (-). It is working for the first evaluation, λlower, but not for the ...
0
votes
1answer
120 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] ...
0
votes
2answers
85 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 $x^{n}=x$. ...
0
votes
3answers
184 views

Clean-up Code / Reduce variables

I'm writing a playing card simulator of sorts, and everything works fine, but some Modules use a disgusting amount of variables. For Example: ...
0
votes
1answer
55 views

function definition, $ symbol apparition after variables [closed]

I have a proble with a system of two differential equations ...
0
votes
3answers
193 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: ...
0
votes
2answers
290 views

Define a function on a parameter argument set to zero

Say I have an expression (matrix) that depends on several variables. f= {{a, b+c},{2a-b^2,c^5+a b}} I want to define new matrices with the single parameter ...
0
votes
2answers
148 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 ...
0
votes
1answer
41 views

How to erase definition introduced by using Set instead of Equal in Solve [closed]

When trying to solve a set of equations, I made a mistake by using = instead of ==. Now when I fixed the mistake, the equation ...
0
votes
1answer
77 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,...
0
votes
1answer
135 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?