Questions tagged [assignment]
For questions relating to assignments to symbols, patterns, or expressions.
299
questions
0
votes
0
answers
19
views
How do I make a formatting rule for a pattern not containing a symbol to attach a rule to
I can define a formatting rule such as
Format[ex[ls_List], TeXForm] := "grgr"
But when I want to define such a formatting rule for a general patter, for ...
- 4,419
0
votes
1
answer
46
views
Problem with SetDelay [duplicate]
I am trying to do some calculations on very long and difficult equations. Ultimately, I want to create a function to NIntegrate my result, but I want to set it as SetDelay (to be evaluated after ...
- 51.7k
1
vote
2
answers
48
views
Multiple assignments of items of a list [closed]
Suppose to have a list of items and two lists of indexes that are parametric and for example are:
l={2,3,5,7,11,13,17}
i1={3,4,7}
i2={4,7,3}
I need a clever code ...
- 23.8k
5
votes
4
answers
598
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.)
- 53.7k
5
votes
4
answers
811
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 $...
- 69.5k
5
votes
3
answers
325
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
...
- 69.5k
11
votes
3
answers
531
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.
...
- 23.8k
0
votes
0
answers
38
views
Formula to resolve max size of subset of set of strings
A set made up by strings, each string contains m characters,
character is either ‘0’ or ‘1'. Now, what is the max size of the subset, which in the subset,
each string has at least n characters differ ...
- 1
0
votes
0
answers
57
views
Strange behavior with setting multiple values simultaneously
I'm having some strange behavior when trying to set multiple variables using {x,y,z} = {1,2,3}.
When I enter "{a,b,c,a',b',c'} = {1,2,3,4,5,6}", it sets a,b,c,a',b',c' to 1,2,3,4,5,6 as ...
- 15.3k
0
votes
0
answers
32
views
How to find clear solution for iterative problem by condition $<v_k ,v_n>=0$ If $k!=n$
I want to find x[n] by v[n] values without x[n] in solution by iterative below problem:
<...
- 83
0
votes
2
answers
77
views
Understanding SetDelayed, ":=" [closed]
Consider the example below,
p = {1, 2, 3};
x = {x1,x2,x3};
fun[x_] := {{1, 0, 0}, {0, 1, 1}} . (p + x);
fun2[x_] = {{1, 0, 0}, {0, 1, 1}} . (p + x);
I expected <...
- 51.7k
0
votes
1
answer
58
views
Delayed evaluation of nested functions
i am new to Mathematica. Here is the situation:
I have a exponential function of n,t that I want to calculate integral over t ...
- 26.3k
1
vote
2
answers
106
views
Replacing Kronecker delta times expression with the expression with inserted index
Consider the following symbolic expression:
expr = f[a,b]*g[c,d]KroneckerDelta[a,m]KroneckerDelta[d,k] + KroneckerDelta[a,p]f[x,a]+const
Could you please tell me ...
- 158k
3
votes
1
answer
134
views
How to assign the following rule?
Consider the following object: function[x,a,b]. It is a symbol carrying one "coordinate" x and two indices a,b.
I ...
- 131k
5
votes
1
answer
219
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 ...
- 107k
-2
votes
1
answer
163
views
How to assign values to x1+x2, x1x2? [closed]
x1 + x2 = -((2 a^2 k m)/(b^2 + a^2 k^2))
Enter the above content and an error prompt will pop up
How to assign values to x1+x2, x1x2?
- 3,947
2
votes
3
answers
109
views
SetDelayed assignment not producing expected result when using ReplaceAll
In Mathematica, I am surprised that the following code does not do what I expect (what I expect is in comments after each evaluation). The problem seems to be due to the fact that when I define test ...
- 28k
1
vote
3
answers
231
views
How can I permute two delayed variables?
Two variables with delayed expression are used for a random number generation:
...
- 759
1
vote
2
answers
151
views
Associating a string variable with a numeric variable
There is a translation operation from a numeric variable to a string variable:
a[i_, j_] := Symbol["a" <> ToString[i] <> ToString[j]]
How ...
- 39.4k
0
votes
3
answers
117
views
Conflicting variables
So, I read a set of variables and respective values from a file and store them in a variable
specs = {{"Type", "KP", "fp"}, {"LP1", 2, 2000}, {"Type", ...
CommunityBot
- 1
3
votes
2
answers
205
views
About how to speed up in assignment
I would like to know if there is a way for increasing the speed of the following computation:
I have a list, let's call it list, and another list of values, val. I ...
- 47.5k
1
vote
0
answers
35
views
Hold around SetDelayed with Graphics [duplicate]
Minimum Working Example
I've defined my own plot function, which does a lot of stuff to the inputs before passing it into the Graphics function. Because of that, I'...
- 450
0
votes
0
answers
56
views
Define a function using output of another function [duplicate]
I am away from my computer and therefore unable to experiment, but I am keen to scribble down a few Mathematica operations in note form ready for my return. So, forgive the simplistic question…
Say I ...
- 2,231
1
vote
1
answer
33
views
Using plot on named expression and explicit expression produces different results
There is some strange behaviour in Mathematica which I don't understand. If you call a function like ContourPlot on two identical expressions (one a named expression, and the other the same expression ...
- 68.4k
2
votes
1
answer
62
views
How to assign a value for specific Indeterminate expressions?
I wanted to form a list as follows
j=1;
Table[(i-1-j)^k, {i,2j+1}, {k,-j,j}]
However, an error message occurred since the list included none positive powers of ...
- 39.4k
0
votes
1
answer
66
views
Error: Invalid integration variable or limit(s) in {-6.28293,0,\[Pi]/2}
When i try to evaulate h at vaule (for example 0), i get a result. When i directly plot the output of h, it also works, but when ...
3
votes
4
answers
465
views
Define a delayed function depending on a global variable as though the variable's contents was pasted
Problem
Say I previously defined a variable (maybe through some extensive calculation)
thing = (a+x)y
Then, I want to use that expression elsewhere. In general, I ...
- 5,857
2
votes
1
answer
289
views
How to assign a value to something inside a module globally? [closed]
Let's say I created a function that calculates something inside a module. How do I assign that result to a global value?
Let's say I have this:
...
- 143k
1
vote
0
answers
89
views
Why =. is not clearing the value of a variable in this case? [closed]
I am reading "Mathematics and Algorithms" as part of the Wolfram Tutorial series.
In "Values for symbols" section of the "Algebraic Calculations" chapter it is described ...
- 333
0
votes
0
answers
35
views
1
vote
1
answer
47
views
Manipulating the list with variables
I am trying to find the maximum element of the list for a given value of variable $c$.
The example of the list is as follows:
...
- 28k
0
votes
1
answer
59
views
Symbolic re-assignment of products
Suppose I have some symbolic tensors $X,Y$ and I want to assign
X.Y
into something else without specifying what $Y$ is. For example, I may want $Y$ to serve as ...
- 11.8k
3
votes
1
answer
111
views
Problem with parametric integral with variable bounds
d[p_, B_] := \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(-B\), \(+B\)]\(Cos[
p\ x] \[DifferentialD]x\)\)
Plot[d[x, 2], {x, -10, 10}, PlotRange -> Full]
I ...
- 51.7k
1
vote
0
answers
47
views
The assignment problem in Plot function [closed]
I used Mathematica to plot a system of equations:
Plot[{y = 2 x - 3, y = x/2}, {x, -5, 5}, Axes -> True,
AxesLabel -> {"x", "y"}, PlotLabels -> {"2x-y=3", "...
- 377
0
votes
0
answers
29
views
Set keeps RHS unevaluated when RHS is a Module variable [duplicate]
Consider the simple code
...
- 1,144
0
votes
0
answers
59
views
Assign different type of balls into output containers with constraints
The problem is to asssign all differend kind inputs to outputs.
For example colored balls.
On the input we can receive max 5 different type of colored balls any with amount.
The amounts for the inputs ...
- 1
1
vote
1
answer
39
views
Delay evaluation of Chop until its argument has no symbols? (== has this behavior, Chop does not)
With Equal (==), if a and b are undefined symbols, a==b does not evaluate. This way we can ...
- 67.2k
1
vote
0
answers
129
views
several actions inside If condition [closed]
Trying to write code with If, if it is correct to perform a number of actions.
I am a beginner user in mathematica and not sure the form of writing are correct.
What I'm asking in simple, this is the ...
- 317
6
votes
2
answers
93
views
Error message not reproduced at reevaluation, SetDelayed cache?
Mathematica v13.0:
nr:=HoldForm@Evaluate@Function[t,x@t][]
then evaluate
...
- 68.9k
3
votes
4
answers
402
views
Defining a function iteratively without Mathematica getting stuck in a recursion loop
I have the following code:
...
- 3,160
0
votes
1
answer
91
views
NIntegrate seems to not recognize multiplication of Piecewise function and f[t_]:= function, Why?
Considering inputs:
vti={0, 1.5, 2.4, 5.0675, 7.735, 10};
Vscc=1.5; PSA=0.025; f=0.6; m=10;
I defined a function "pwtemp2", using "FC1" and &...
- 131k
1
vote
0
answers
45
views
How can I access to the needed part of this expression? [duplicate]
I have defined a list like this:
F[1][t] = ConstantArray[a1, 10]
Now I want to assign to some of the elements the value 1; I ...
- 6,687
1
vote
0
answers
153
views
Extracting expressions from LHS of an assignment
I need to list all variables in a notebook containing several Set assignments, lhs=rhs, and equations, ...
0
votes
1
answer
55
views
Program works, but then fails when I write it inside Module [duplicate]
I'm new to Wolfram Language; I'm trying to get used to it by writing a bunch of code and programs, being one of them the algorithm for the bisection method.
When I write the algorithm outside of a ...
- 13.7k
3
votes
2
answers
154
views
How to make c[n_, x_, y_] := ToExpression["p" <> ToString[n]] = {x, y} work?
I am trying to do the following:
c[n_, x_, y_] := ToExpression["p" <> ToString[n]] = {x, y}
That is: Evaluating ...
- 158k
0
votes
1
answer
133
views
Forcing mathematica not to substitute some terms in an expression
I have an expression c which should be defined before the function and a function f defined as follows:
...
- 8,217
0
votes
0
answers
117
views
Can't create matrix function of symbolic functions and assign values to elements
So I have a problem regarding the symbolic matrix value assignment.
Say I create a matrix function as:
P[t_]:= {{P1[t]}, {P2[t]}, {P3[t]}};
Then I want to assign ...
0
votes
0
answers
55
views
How to use Mathematica to return value from for-loop [duplicate]
I tried to use Mathematica to implement random generator. The pseudo code I use is as following:
...
- 47
0
votes
1
answer
80
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 ...
- 763
0
votes
0
answers
57
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 ...
- 1,607