Questions tagged [assignment]

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

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0answers
31 views

Programmatically Inject Logical Vector into Manipulate Checkboxes or Vice-Versa

I am building a large Manipulate application with about 50-60 checkboxes through which the user can select entities to be drawn on a main canvas. The main drawing routine, called from within ...
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2answers
57 views

Error in Assignment

I want to create a matrix with each element updated as per the formula, whose inputs are dependent on the location of element in the matrix. ...
1
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0answers
25 views

Un-assign MenuCommandKey

In my StyleSheet, I would like to assign to the environment Subchapter the Key Alt+2 (via MenuCommandKey. However, this is ...
1
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2answers
89 views

How to assign output of `Last@Reap` to a variable? [closed]

I would like to define a variable that equals the solution of a numerical equation. Usually something like smax=zmax/.FindRoot[Exp[-zmax/2]==2,{zmax,0}] would work. ...
1
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1answer
39 views

Why does it fail to assign values to variable in Grid? [closed]

I have a grid such as the following, and want to assign the values in the second row to the variable in the first row, but it always fail, can you provide a solution? Thank you! ...
0
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1answer
38 views

I am asserting a variable in Mathematica as Real yet it is not implementing it!

Element[\[Theta], Reals]; Ga = g; Gb = g*Exp[I*\[Theta]]; {{Conjugate[Gb], Ga}, {Ga, Gb}} I have a code as such for a matrix as given above. as ...
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0answers
21 views

Assign a Derivate to a new fuction variable

I'm having a new problem. I'm trying to create a new function from a Derivate of another function, but i'm can't getting it. Someone could help me? I'm thinking that is something in the syntax of the ...
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2answers
31 views

A question about a replacement of element of set

To begin with, I'm a poor English speaker, which means it would be hard to read to natives... I was trying to memorize mRNA codons with mathematica. ...
1
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1answer
64 views

How to use an up-value assignment when all symbols are “too deep”?

I would like to make an up-value assignment such as a/:Conjugate[a[x]]a[x]+Conjugate[b[x]]b[x] = 1 or ...
0
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1answer
54 views

Replace constant in summation function using replace or If or /

Hi i how do i replace constant for k in this summation. For following: Even 2*n Even replace k by a Even 2*n+1 Odd replace k by b Here is the code ...
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0answers
54 views

Making a function definition where the right hand side is evaluated before the definition is saved [closed]

My question is about assigning the resulting expression after evaluation of a function. So what I want: FOCf[x, y] := D[f[x, y], x] such it immediately ...
3
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2answers
115 views

Is it possible to set values for a list of variables using a for loop? [duplicate]

Let me preface this question by noting that this is a simple example meant to clarify what I am asking. The actual context in which I want to implement this involves associations containing hundreds ...
4
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2answers
120 views

Scoping of pattern variables [duplicate]

I have run into a problematic behavior, and then came to find that it is a "possible issue" called out in the documentation, but I guess I am just baffled that this IS an issue, and am wondering why. ...
-1
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1answer
56 views

Why it is doing part assignment? [closed]

I am writing an algorithm and need to keep updating an association called "verticesAssoc". My algorithm ran perfectly at first. However now I want to use the same algorithm on another association "...
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0answers
20 views

Seeing definitions of built-in functions [duplicate]

Possibly a very amateur question, so I'll apologise in advance. I'm reasonably new. I'm trying to write a Dot equivalent of ...
6
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1answer
64 views

unexpected result from augmented assignment to association

Is the last of these results expected? If so, how? ...
3
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2answers
175 views

Transferring DownValues

I have a code in which I define something like this: cc[1, 2] = 1; cc[2, 6] = 12; cc[3, 7] = 3; After some manipulation I define a sort of temporary variable ...
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0answers
43 views

Reassignment of variables

Another quick question of mine. If I want to assign variables to be some arrays in parallel, I can use a construct like ...
2
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1answer
76 views

Reassign a value to an array element

I have a very complex code in which I assign a value to an element of an array and then I reassign to it another one. A minimal example: ...
1
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1answer
64 views

Evaluating the 1st argument of Set

I want to assign a certain value to an element of a tensor. This element is identified by an array obtained from some evaluations, so we fix it. Here i present an oversimplified core part of my code: ...
1
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1answer
348 views

Tag Times in Null is Protected [closed]

I've some problems with the error mentioned in the title. Unfortunately, my code is full of subscripts so I'll show it in a photo. In this code the central aspect is to assign a scalar value to an ...
1
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3answers
144 views

Assign a function within a function [duplicate]

What I'm doing wrong? 1st function works as expected but the 2nd one doesn't. What I want is to enter an algebraic expression and two numeric constants and get the same result as with the first ...
1
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1answer
45 views

How to use a calculated expression on left-hand-side of an assignment?

Elementary question, I guess: I have a left-hand-side something like this: ...
0
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0answers
54 views

Trouble with UpSet(Delayed) and IgnoringInactive

I'm having problems setting an upvalue for a symbol that is supposed to ignore Inactive: IgnoringInactive[f[g[x]]] ^:= match; ...
0
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2answers
50 views

Hot to single out numeric values from NMaximize

I have some problem with NMaximize. The function NMaximize gives result like this NMaximize[f[x],x] {f[xmax] ,{x -> xmax}} I've read in various answers that ...
3
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1answer
86 views

assignments within Manipulate

I have encountered unexpected behaviour when assigning variables in Manipulate. Consider an inverted parabola y[x_, c_] := -x^2 + c The following code finds the ...
0
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1answer
60 views

Symbolic variable assignment

I looked around and didn't see this question on the forum, so my apologies in advance in case this has been answered here. My question can be concisely described by the following example: ...
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2answers
89 views

How to assign values using nested Part[ ] expressions?

Why doesn't this work? Can I make it work? ...
0
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2answers
89 views

How to 'unassign' variables used for PlotPoints, which subsequently print as e.g. Charting`Private`pvar$727158

I have a table of four insoluble equations, fceq, in terms of unassigned variables, Subscript[fc, i], Subscript[μ, i]. I am using contour plots to visualise ...
11
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2answers
1k views

Can't understand one paragraph in Power Programming with Mathematica

In the chapter 7 of the Power Programming with Mathematica, there is a paragraph discussing the behavior of Set- functions: (page 205. (pdf version p. 224)) ...
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1answer
32 views

Assigning eigenkets to particular eigenspace depending on eigenvalues of system inside a module

I am writing a module, in which the Observable and State is given, so I need to write a function/module QuantumMeasurement, that will return a state of the quantum system resulting from the ...
0
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0answers
39 views

assigning numerical values to variable

I have a csv data file, has two columns of data. First column denotes time (t) and the corresponding value in the second column is flow rate (f). I would like to assign these values to an array f[t], ...
1
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2answers
56 views

Assigning variables whilst in a context

When working in a context, I would like all variable assignments to happen on symbols in the new context. This doesn't normally happen. For example, ...
5
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2answers
144 views

How to set parts of Associations “named with” SubValues

Parts of Associations can be set with the following syntax: as = <|"a" -> 10|> <|"a" -> 10|> as["b"] = 20; as ...
2
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0answers
55 views

Writing a variable to file with its value, not its name [closed]

This is my first time ever posting a question about Mathematica anywhere, so please excuse my ignorance. I'm trying to save a ColorFunction to file, but can't get the variables to be written as ...
2
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1answer
113 views

Generalization of the probability of union

hi How can I do for mathematics to expand this equation for any value of the variables i, j, k
3
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0answers
445 views

Multiple variable assignment from a list

For example in Python, if we have a list of 3 elements, say ls = [1,2,3] and we want to assign a variable to each value (from left to right), one can do as follows: ...
2
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0answers
65 views

Matrix as function manipulation

Consider matrix mat[x_] := {{1, 2}, {3, x}} with mat[x][[1]] giving {1, 2} I wanna ...
11
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2answers
2k views

How to pass variables by reference and by value [duplicate]

I haven't seen this question specifically addressed before in this site, although some hints and traces have been given, for instance, here: Pass by reference for an option argument Does pass-by-...
5
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1answer
69 views

Set on symbol with OwnValues skips UpValues

Can anyone provide insight on what's going on here? First I define a new Set behavior for a symbol: ...
2
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0answers
92 views

How do I assign a value to a[1,2][[3]]?

How do I assign a value, say 7 or "t", to a[1, 2][[3]]? a[1, 2][[3]] = 7 and ...
2
votes
1answer
25 views

Refer to solution from matrix [duplicate]

Consider matrix equation m = {{1, 2}, {3, 4}} l = {{1}, {0}} p = {{p1}, {p2}} eq = m.p == l Solve[eq] Output is {{p1 -> -2, p2 -> 3/2}} But p1 and p2 do not ...
8
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2answers
199 views

Confusion about HoldFirst attribute of Set

Set has the attribute HoldFirst. Expectedly the following does not work, i.e. it does not assign the OwnValue of 3 to x: ...
9
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1answer
347 views

Part not behaving the way I expect it to

p = {{1, 0, 0}, {0, 1, 0}, {0, 1, 0}}; p[[All, 3]][[1 ;; 2]] = {1, 1}; p I want to replace the first two elements of the third column of a 3x3 identity matrix. ...
4
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2answers
217 views

Wrongly assigning a value to an expression

Sometimes I misstype an equality and I write an assignment instead. For example, if I write f'[x] = 2 instead of an equation, ...
3
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2answers
113 views

HoldFirst and Hold expression as argument

I store a reference to the association in a held expression in a variable: a=<||>; b=Hold[a]; And in the code, I want to do manipulations with the original ...
3
votes
0answers
48 views

Variable assignment/replacement issues

I have three questions about variable assignment. Module[{z}, z = y; p'[y] /. p -> Function[y, Evaluate[z]]] When I run the above code, it outputs 0. 1) If I ...
4
votes
1answer
108 views

Assignment via iteration over list of variables to be assigned values

Variations on my question have been asked before (How to re-assign values to a List of variables?, How to use Table to assign values to variables in a list?, Assigning values to a list of variable ...
4
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2answers
88 views

Combining SetDelayed, Set and Options [duplicate]

A function can be defined with SetDelayed while storing its value with Set, eg: ...
5
votes
2answers
69 views

Vectorized AssociateTo

With an Association we can update keys in place two ways: ...