Questions tagged [scoping]
Questions on Mathematica's scoping constructs (Block, Module, With, etc.)
399
questions
1
vote
2answers
56 views
Sum of n sums, Permutations of the indices, how to write them in Mathematica?
I was wondering how to write a function $ F (r, q, n, f) $ in Mathematica, defined in this way:
$$F(r,q,n,f):=\sum_{i_0=1}^q f(i_0) \Biggl(\sum_{i_1=i_0+1}^{q+1} f(i_1)\biggl(\sum_{i_2=i_1+1}^{q+2} ...
0
votes
0answers
30 views
Can I still use global variables when I choose the default context to be the cell group?
To avoid accidentally reuse the same variables in different sections of my notebook, I go to Evaluation menu and choose Notebook's default context > Unique to each cell group.
But sometimes I do want ...
4
votes
1answer
108 views
Best practice with Return in Module or Block
I am a bit confused on the use of Return in either Block or Module when defining a custom ...
5
votes
2answers
133 views
Using `With[…]` with a list specification as a variable
If you have some defined function, say f[a_, b_ c_, x], one can initialize this by using With[...] as
...
2
votes
2answers
68 views
Scoping construct for dependent constants
I sometimes want to write a function which needs to apply a bunch of transformations that are not functions of a single parameter only:
...
3
votes
1answer
116 views
function evaluation - I don't get it
this function returns Pi/4 for a[1,4]
In[...]:= a[r_, n_] :=
Module[{an = Pi/n, h = r Cos[an], w = 2 r Sin[an]}, an];
a[1, 4]
Out[...]= Pi/4
so the kernel ...
5
votes
1answer
104 views
why DSolve in V 12 returned an internal module variables with $ on them in this example?
Fyi, Reported to WRI in case it is a bug. [CASE:4288939]
Is this supposed to happen?
...
0
votes
0answers
26 views
Why are unrelated symbols localized in Module? [duplicate]
As I understand, an expression like Module[{var},expr[var]] localizes var and evaluates ...
1
vote
1answer
94 views
How to use Module function?
Here is my issue; I want to iterate a fit to this data for a polynomial of degree 2 up till degree 6. However, at each iteration I drop certain data points that have a poor residual value. So each ...
0
votes
1answer
38 views
Modifying/optimizing a double sum with an If condition
I would like to better understand double summations where one of the sums depends on the upper limit of the previous sum. This appears frequently in representation theory (to the extent of my ...
1
vote
1answer
52 views
Variables referring to other variables within Module
The following doesn't work:
Lol[x_, y_] = Module[ {w=x+1, z = w + 1}, z]
because z refers to ...
1
vote
1answer
58 views
Using rules inside Module or Block
I have a rather long piece of code inside a Module, and I want to provide different parameters to the different pieces inside the ...
0
votes
1answer
54 views
0
votes
0answers
23 views
Gradient method in vectorfield on surface table does not work, module is slow
For teaching purposes I want to generate a vectorfield on a surface an visualize the path of the gradient method.
The surface and the gradient are generated by
...
10
votes
4answers
541 views
What is the accessibility of a package's `Private` context variables?
I've been reading up on how Mathematica handles contexts, $Context, $ContextPath, and a few of the tutorials they have on ...
6
votes
1answer
119 views
RegionPlot3D no longer localizes its arguments?
Bug introduced after 9, fixed in 12.0.
Just now, I was astonished to find the behavior of RegionPlot3D changes somewhere after v9 . Consider the following sample:
...
3
votes
1answer
74 views
How to trace value assigned to local variable(variables in Module)?
Bug introduced in v10.1 or earlier and persists through v11.3
CASE:4240757
Here is my code:
...
0
votes
0answers
52 views
Assigning values to variables inside Module using user defined function
Say I'm defining a function
with some local variables, for which I'm using Module. Now, I want to assign some value (or perhaps a list of values or a list of list, ...
1
vote
1answer
97 views
Why are there local variable conflicts in my recursive function definition?
Sorry to post a long piece of code. There are two places in here where I Print[] 'path2' when the count == 984, because for some reason, that list is getting ...
0
votes
1answer
74 views
Different result in ContourPlot function using different version of Mathematica (?)
I tested "Elasticity with Mathematica" notebook (Mathematica 6) in Mathematica 11.3 and tested C05_stress_kirsch.nb, I added some trigger code to protected function in the tensor2analysis.m file, and ...
2
votes
0answers
25 views
1
vote
0answers
46 views
Why doesn't `ReplaceAll` work in this situation? [closed]
I can work around this by using With, but it seems really odd to get the following:
...
0
votes
1answer
79 views
Multiple functions within a Module
I have a function that extracts a numerical value from two vectors, written as Spa[i_,j_]:=Flatten[LaU[i].LaD[j]][[1]]. (Note, I'm sure that this isn't the most ...
1
vote
0answers
51 views
Function returned from module doesn't work [closed]
I have a sequence of steps that work in the main notebook:
...
0
votes
1answer
83 views
Finding the inverse of a function
I am to solve for $r(\rho)$ given the function,
\[Rho]Asymp[r_,b_,q_] := 1/(1 - q) Gamma[1/(1 - q)]/Gamma[(q - 2)/(q - 1)] r Sqrt[1 - (b/r)^(1 - q)]
This can be ...
1
vote
1answer
33 views
Evaluation of Extract and use the result in a Sum
I am experiencing a problem in the evaluation of a sum. I hope that someone can help me, I am not an expert Mathematica programmer. I'm posting just the portion of code that gives problems, I know ...
4
votes
2answers
130 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. ...
0
votes
1answer
130 views
Can I bake my own PI using your Wolfram language oven and prebuilt utensils? [closed]
How might I override the value of the Greek letter PI within various builtin language functions in the Wolfram language? Specifically and without having to reinvent the wheel or code equivalent ...
2
votes
1answer
58 views
How to define a function inside a module through Evaluate [duplicate]
I am trying to define a function inside a module as following
...
0
votes
0answers
47 views
Symbol created in Module not seen outside of Module scope [duplicate]
I am using a function defined with a Module[]. In the Module I am creating a new variable name using a ...
1
vote
0answers
52 views
ConditionalExpression still resulting from Assuming a Module's local variables
I have a memoizing, recursive function whose MWE looks like this (the two fake inputs/ICs are from 'K' and 'Bfun2', the latter just a quick way to check the results coming out of the Residue.:
...
1
vote
2answers
84 views
How do I localize changes to a variable inside a Do-loop?
I want to change the increment value inside the do loop . But i dont know why it remains for the first declared value?
...
3
votes
3answers
103 views
MostOccuringWeekdays Wolfram Challenge [closed]
I am working this challenge from Wolfram Challenge. I believe that I have solved the problem with the following code (note it is not very efficient - I am new to Mathematica!)
...
3
votes
1answer
62 views
Module - Symbols out of scope of lexical scoping
The Problem
Consider the following code (1):
In[1]:= x = 2;
Module[{x, y},
y[x_] = x;
y[1]
]
Out[2]= 2
I expected the answer ...
3
votes
3answers
220 views
What is wrong with Module? or me? [closed]
The following code does not give me an answer. It looks all is working when each command inside Module is individually run. But ...
2
votes
1answer
47 views
Why does Mathematica stay on an endless evaluating loop with Manipulate?
I have built Manipulate to see the impact of a change in time and volatility to the profit of an option strategy, bull spread.
To calculate the price of the option, I built the good old Black-Scholes:
...
5
votes
1answer
139 views
With vs. Block scoping of parameters for Plot
A very basic question..
Why does Block work, but not With, to specify value of a parameter for a function to be plotted?
...
5
votes
2answers
91 views
HoldAll Attributes and Delayed Evaluation: ContourPlot with solutions to NDSolve
This is a general question on evaluating functions that are defined to be evaluated with delay.
In particular, I am having difficulties working with the ...
1
vote
3answers
72 views
Prime number counting function
As part of an assignment for a calculus class, I have to write code for the prime number counting function $p(n)$, I have no problem creating the function itself, but for I want it as a function, ...
6
votes
0answers
63 views
Nested rules and automatic renaming of variables [duplicate]
I understand why $ happens here:
ClearAll[foo]
foo[a_] := (x_ :> a x)
foo[1]
...
0
votes
0answers
39 views
K vs k in a module
Module[{K = 1, fn}, fn[p_] := Print[K];
ParallelTable[fn[p0], {p0, 2}]];
Prints K$316 (or whatever the module counter is on)...
1
vote
0answers
49 views
What use is empty binding list in `Block[{},…]`? [duplicate]
Spelunking the Export function, I stumbled upon the following definition:
...
1
vote
1answer
70 views
1
vote
1answer
59 views
Problem passing argument in hash table from global context to a module
I was experimenting with passing arguments via a hash table to a module. Found a very strange result. When I pass a function to be plotted inside the module, it comes out empty.
Yet all argument ...
2
votes
1answer
80 views
Module and With do not work in some cases
I apologize if the title is too vague/general but I couldn't find a better one. I am trying to use either Module or With but it does not work if the object containing the local variables is defined ...
7
votes
0answers
126 views
A bug in Derivative?
Update
This is a bug in v11.3 or earlier and is fixed in v12.
Original Post
Check this out:
...
0
votes
1answer
74 views
Want help with debugging a For-loop
I'm trying to run a simulation, which at the end gives a value 'qber'. Now I want to run this simulation multiple times with different values of 'p' each time. And these value of 'p' are actually the ...
2
votes
2answers
149 views
Clear variables inside Module
I have a function that uses Module. The function takes as input a .csv that can have as many columns as it wishes to, and it ...
5
votes
4answers
208 views
Create rule whose LHS is already defined
My question will be clearest if defined using an example. Consider the following code:
Func[k_]:=Block[{a},
a[t_]:=t^k;
{a[t]->a[t]}
];
However, calling ...
1
vote
0answers
44 views
Dependent variables in With operator [duplicate]
I want write something like this
With[{x=1, y=x+1}, y]
and get 2 as an answer. What is the correct way to do this?
