Questions tagged [assignment]

For questions relating to assignments to symbols, patterns, or expressions.

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1answer
31 views

any way to store the values of the controls of a Manipulate so that one can reuse them in the future excutions

I’m using Manipulate[] to adjust several parameters, which will eventually generate some figures. After I get the desired view, I’d like to store the set of control parameters so that I can reuse them ...
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0answers
48 views

Block Behavior, but for Function Assignment instead of Variable Assignment

We can define a function using a variable b that does not appear as an argument, and then using Block, change the output of the ...
2
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1answer
112 views

Cannot assign variable value inside Do Loop

This is more of a conceptual problem. Suppose I have three lists. x1 = {1, 2, 9, 10}; x2 = {5, 6, 7}; x3 = {9, 10, 13}; Now, I wish to keep only the first two ...
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1answer
60 views

Avoiding For loops to perform an assignment to a variable with indices of user-choice [duplicate]

I am looking for an efficient way to perform the following operation without For loops ...
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0answers
29 views

Going between assignment rules and functions

I am trying to develop a model using Mathematica, and continuously run into difficulties going between the outputs of various functions (Solve, Differentiate, etc.) and back to functions (in the ...
4
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2answers
79 views

Assignment with Span to Indexed Variable

If I use span to assign a value to every element in a "column", it miraculously works: ...
2
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1answer
126 views

How can I list the common elements of two lists?

The elements of both lists are given as A={9,5,9,3}, B={9,9,5,5} In this case, how can I list the list {9,5,9} of the common elements of the two lists? (The order does not matter.)
1
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1answer
95 views

pure function assignment

I do not understand this statement from the Introduction to Dynamic tutorial: ...
2
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0answers
56 views

Certain plotting functions are setting variables unwantedly

I came across the following problem. Certain plotting functions set variables to values, which I do not want. For example, if I run SliceVectorPlot3D with an ...
2
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1answer
52 views

How can I transform equation results into an array of values? [closed]

I would like some help. I executed the following code: Solve[Det[(s IdentityMatrix[2]) - A] == 0] which yielded the following results at the output: ...
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0answers
53 views

Proper way to construct a function that takes too long to plot and integrate

Consider the functions phi[t_] and psi[t_] defined in the code below. These are used as basis functions for interpolation ...
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0answers
77 views

Fast definition of sparse tensor

I'm defining a sparse array through ...
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0answers
25 views

Extract actual result from equivalence [duplicate]

When I get a result like this {x -> -0.5 - 0.866025 I}, how do extract just the number: -0.5 - 0.866025 I. I can do this with the .rhs() method in Sagemath but I can't find the function in ...
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1answer
50 views

Why does the delayed functional assignment evaluate to `5=6`? [closed]

Why is it that x=5 x=x+1 nicely evaluates to 6, but the following ...
2
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0answers
56 views

Referring to matrices with index [closed]

For exampe I have two matrices, with index 1 and 2 Mat[1] = ConstantArray[0, {2, 2}] Mat[2] = ConstantArray[0, {2, 2}] I wanna assign new value with ...
2
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2answers
100 views

How can I get output from Reduce assigned to a variable? [closed]

I use Reduce to solve an 3rd order equation, and the output is given as the OR'd combination the solution variable. Normally, I can do a replacement to assign the value to a variable, but that doesn'...
1
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1answer
45 views

How to list automorphisms on a finite set and analyze them

Let s be a finite set of integer lattice points, for example s = { {0,0} , {0,3} , {1,1} , {0,2} }. I am trying to do two things:...
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4answers
65 views

Only Reals Rules

I have a huge array of rules with many variables, such as ...
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0answers
50 views

Errors with assigment and no errors with replacement rule, why? [closed]

So I have an expression, let's call it f11 which is a function of t of this form f11= a1*t^(-4)+ a3*t^(-3)+... and so on up until a finite positive power of t. In ...
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1answer
34 views

Using results from Nmaximize in loop

I try to Append the vector S by z+x whereby z and ...
0
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3answers
63 views

Assign value to the symbol returned by function

Ok, so here is example code: Clear[p, flag, k]; p = 2; k = 1; flag = True; If[flag, p, k] = 0; p After that I get the message ...
3
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2answers
124 views

Set value in a list at given position

Consider r = Array[Total[{##}] &, {3, 3}] (*{{2, 3, 4}, {3, 4, 5}, {4, 5, 6}}*) pos = {{1, 1}, {2, 2}}; vals={100,200} This ...
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2answers
75 views

Using a list as arguments in a function

This might sound a little silly question but I cannot get my code work. Here is the problem: I have quite a few lists of data which are basically beam profiles. I am using ...
2
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1answer
55 views

Number of values stored in a function

Suppose I run this: f[0] = 1; f[n_] := f[n] = 2 f[n - 1]; f[1000] Now there will be 1001 values stored in f, and ...
1
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2answers
41 views

How can I use Part Assignment to change sublists into other sublists (without changing levels)?

Here's a 5x5 grid. Using predefined starting points, I'd like to change some sublists into something else (e.g., the values for a color, "drawing an opaque box"). ...
3
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3answers
415 views

Changing value of specific element in an array. (Converting code from MATLAB to Mathematica)

Can we change the value of a specific element of an array in Mathematica? Basically, I have the following given MATLAB script which writes a big 3N-by-3N matrix $h$ by combining two 3-by-3 matrices $...
1
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1answer
57 views

Scan and Set over multi-dimensional data

Suppose I have the following: Table[x[i,j] = f[i,j], {i,1,10},{j,1,10}]; I want to set variables x[i,j] to have value ...
1
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1answer
58 views

Default Options not working in user-defined function for SymbolName

Abstract I have a function objectName[symbol] that returns the SymbolName as both a standalone function or when nested inside ...
1
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1answer
66 views

Setting a function equal to another function then Clearing the latter

I have a loop in which several values of a function are computed, depending on the values for that function that were computed in the previous iteration of the loop. This could be implemented ...
1
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1answer
67 views

Set: in part assignment is not a symbol [closed]

This is probably a basic question but I am new to Mathematica, so please help me out here. I have the following piece of code: ...
2
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2answers
52 views

Cannot understand meaning of "identical"

This came up in the context of plotting solutions to NDSolve, but I've reduced it to the following issue. This really has me scratching my head. ...
4
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2answers
98 views

Using pure functions to assign a value to variable depending on whether it has been defined already

Let's say I want to assign to a variable the value $2020$ if it has not already been defined and do nothing if it has. In short, for a variable $a$, I want to achieve the functionality of ...
6
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4answers
228 views

Assigning a string to variables names

I have the list n1 = {{REL1, "REL.csv"}, {RAND1, "RAND.csv\"}}. That is {{variable name, string}, {name, string}}. I want ...
2
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1answer
45 views

Problem with superscript

I would like to know if there is option to make such scrpits like in this picture below. Is option to put letter instead of a *?
4
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1answer
104 views

Why the difference in performance? Array vs List and `Delete` vs `Nothing`

In a previous question I was warned against the use of Nothing to delete elements from a list, and rather use Delete. Being of ...
7
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1answer
105 views

How would you explain Nothing[] weirdness? [duplicate]

I would like to use Nothing[] to make some elements of a list invisible. (The intended use is to remove a few unwanted points from a ...
9
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1answer
132 views

Why Optional in Set is not held by the HoldFirst attribute?

When evaluatingf[x_:x0] := x, x0 will be evaluated, regardless of the HoldAll attribute of <...
4
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2answers
191 views

Using module to define a function that calls another function: Should i use set-delayed (:=) or set (=)

Suppose that I have a function f[x_,y_,z_]=x*y*z and now suppose I want to consider a specific application where z is a ...
1
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0answers
102 views

What does a single vertical bar mean in ConditionalExpression? [closed]

I got the condition below as part of a ConditionalExpression. Those single vertical bars before and after $\frac{1}{k1}$ appear to be an absolute value but I don't ...
0
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2answers
141 views

Assign FindRoot output vector to a vector instead of element by element

Using FindRoot to solve a multivariate equation system, assigning the output to variables one by one works, but assigning the output vector to a vector gives the ...
0
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0answers
28 views

Performing operations on LHS of assignment [duplicate]

Is it possible to first perform an operation on LHS of the = symbol, evaluate that, and then assign the RHS to the new LHS as usual? The following shows the most ...
1
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2answers
76 views

Assigning values to multiple variables from a list

I have a solution of the following form: $F(x)= \\ \qquad c+(x_0+x_1+x_2+\ldots +x_n)- \\ \qquad (x_0\,\log(x_0+\sqrt{x_0})+x_1\,\log(x_1+\sqrt{x_1})+x_2\,\log(x_2+\sqrt{x_2})+\ldots +x_n\,\log(x_n+\...
5
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1answer
114 views

Setting options of object after defining it

Is it possible to edit the options of an object like Plot or Graphics after I store it as a variable? For example, consider the ...
1
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2answers
73 views

Assign numerical values to symbolic variables in a vector inside a do loop

I have vector k = {k1, k2, k3, k4, k5, k6}. I would like to assign numerical values to the elements of k in each step of a <...
0
votes
1answer
114 views

How to turn a matrix into a 'function'? [duplicate]

I have some codes to turn a set of equations into a matrix. Suppose the matrix Lis expressed in terms of variables $\epsilon$, $K$, $M$, and I want to make a ...
4
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2answers
280 views

What is the point of tagset /:? [duplicate]

I'm teaching myself Mathematica and came across tagset. So I followed the example in the link, but seem to be missing the point. All of the below give me the same answer after assignment: that ...
1
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1answer
53 views

TagSetDelayed for spotting zero derivatives

I am trying to implement my own differential operator, d[arg_, var_], that computes the derivative of arg w.r.t. ...
1
vote
1answer
54 views

Part Assignment of variables with argument

I do not really understand why this: a = {1, 2, 3}; a[[1]] = 3; a {3,2,3} works as desired, but this does not: ...
2
votes
1answer
77 views

SetDelayed error for Derivative rule

Having a delayed assignment of the form Derivative[1][f][x_] := HoldForm[f[x]] works. But if there is a delayed assignment for f as in ...
8
votes
1answer
143 views

Error Message when nothing should be evaluated

When I try to define this simple function getCoeff[SeriesData[_, _, coeff_, _, _, _]] := coeff[[2]] I get an error: ...

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