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
0answers
42 views

Subscripts in variable names: Bug?

In the following plot, one of the two functions {-par, par} defined by ...
1
vote
0answers
108 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
161 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
59 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
73 views

Why the variable cannot use subscript? [duplicate]

Today,I use the Lagarange method to deduce the robot 's dynamic equation .I use the mma to help me calculate. I want to use $$x_B,y_B, v_{Bx}, v_{By}, v_B ^2$$ to represent the point B 's ...
1
vote
0answers
2k 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
182 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
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 ...
0
votes
3answers
76 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
2answers
116 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, ╬╗lower, but not for the ...
0
votes
1answer
87 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
77 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
161 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
3answers
92 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
141 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
65 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?
0
votes
1answer
68 views

How I can define a new function as a function argument?

I need to pass a function with t as independent variable as a function parameter and want to create a new function of the same through this provided the argument of another function. Here is my code. ...
0
votes
1answer
46 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
43 views

Indexed variable with alternatives

I have a["tree"] := "oak" a["flower"] := "rose" a["dog" | "cat"] := "animals" I want that the last definition of a behaves ...
0
votes
2answers
165 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
1answer
117 views

Arbitrary number of variables in Module, Block, etc

How do I specify an arbitrary number of variable names and initialize them inside of a Module or Block? For example, I want to do something like: ...
0
votes
1answer
49 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 ...
0
votes
1answer
48 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 ...
0
votes
1answer
109 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
102 views

About Symbolize and Variables

I do believe this sort of similar questions had been asked many times, so I have read a LOT. For example this and this as well as many other related posts. But a glance at what my main question is ...
0
votes
1answer
32 views

Why would this function work only when I make a copy of the variable? [duplicate]

Why would this function work with a copy of the function variable: ...
0
votes
3answers
140 views

Identifying the symbol which has a specific value

I'm writing a program that will solve the value of 1 variable in a 4-variable equality equation, but the variable to be solved will depend on the user's input to the program. This is what I've come ...
0
votes
2answers
170 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 ...
0
votes
1answer
90 views

Collecting variables from Subscript

I have followings set: t = Transpose[{x[#] & /@ Range[20], RandomInteger[15, 20]}]; Subscript[#[[1]], #[[2]]] & /@ t The code is just to build my set.So ...
0
votes
0answers
13 views

mathematica online variable naming [migrated]

I am new in mathematica Doing my best, still I don't know how to use a variable with a length higher than one. Here I use a variable called ba while wolfram alpha ...
0
votes
0answers
47 views

Errors when changing variables

I have the following function : K[r_, h_] = -(D[h[r], {r, 2}] + D[h[r], r]/r + D[h[r], r]^3/r)/(2 (1 + D[h[r], r]^2)^(3/2)) In order to adimension it, I am ...
0
votes
1answer
46 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 ...
0
votes
0answers
34 views

Variables input generation for Minimization in High dimensional space

I'm currently doing optimization in a high dimensional space. I was thinking of giving FindMinimum (or NMinimize not certain ...
0
votes
0answers
14 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: ...
0
votes
0answers
84 views

Numerical Integration/Function

I have a problem with a function defined numerically through an integral of the form: ...
0
votes
1answer
67 views

How to assign the array data to variables?

A very basic question but puzzled me for long time on how to assign array to variables. For instance, we have array {{t1,x1},{t2,x2}...{tn,xn}} how to assign the first element to variable t and ...
0
votes
0answers
11 views

Watching variables during Notebook work session [duplicate]

One feature that I have always wanted but could not find out if it was supported and that is to actively watch variables and their values while working in a Notebook session. In fact, there are two ...
0
votes
1answer
28 views

Variable as Difference of 2 Variables

I would like to evaluate a function based on the absolute difference of two variables. An example: g=5*x-5*x*y-5*y diff=x-y D[g,x] D[g,y] D[g,diff] I cannot find ...
0
votes
0answers
22 views

SharedVariable in WebMathematica

How can I create a variable to be used and setted over all my WebMathematica kernels? Here is the case: Create a package with do data structure like: data = ...
0
votes
0answers
46 views

Replacing variable names in a notebook

I am working on a code that simply imports and graphs a function. If I preset the directory I would have something that looks like this: ...
0
votes
1answer
41 views

Reducing Output length by introducing new variables [duplicate]

I have outputs like "expression/(1+3*c^2) +anotherexpression/(1+3*c^2)" and so on. Is there any way to set 1/(1+3*c^2)=A where A is a new variable so that the output reads like ...
0
votes
0answers
55 views

Coupled ODEs with boundary conditions - DSolve Error

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 ...
0
votes
0answers
39 views

Can the value of a variable be made to persist between front end sessions? [duplicate]

For example, say I create a notebook with a cell a = 5 + 2 and then I close Mathematica, reopen the notebook, enter a new cell ...
0
votes
0answers
36 views

Get value for a variable from user inside a module [duplicate]

I am writing a module. When I run the module, I want it to ask for a variable, like I can in other programing languages such as C++ or Python. For example, in C++: ...
0
votes
0answers
104 views

Is there a better way of creating/assigning variables programmatically than using strings and ToExpression?

For quite a while now I've been wondering how to assign variables programmatically, and I have finally figured out one way of doing this. For example in a game where you have a variable number of ...
0
votes
0answers
31 views

How to change $n$ variables with $n$ Buttons automatically [duplicate]

I was trying to make a little game, and I came accross this problem. The goal is simple. There are going to be $n$ number of buttons, and each one will change a value of one variable. For example, ...
0
votes
0answers
64 views

How to hide global variables in package?

in the package I'm writing I have a list of global variables which should not be visible from a notebook. Here's an extract of the package: ...
0
votes
0answers
46 views

Block, With, Module, can anyone help me understand the distinction? [duplicate]

I've been working heavily with Block[] for months in my research so I've read the documentation for the seemingly similar commands With[], Block[], and Module[]. Personally, I've had by far the ...
0
votes
0answers
102 views

Local variable names - Is there an easy way?

I apologize first, because this has been asked, like in Treat all variables as local in a module [duplicate] Variable scope similar to other languages But I don't get how to use them. Some codes ...
0
votes
0answers
39 views

Varying number of function arguments [duplicate]

I have a function of six arguments: ffit[q1_, q2_, q3_, q4_, q5_, q6_] := (a1*q1^2 + a2*q2^2 + a3*q3^2 + a4*q4^2 + a5*q5^2 + a6*q6^2) ...