Linked Questions
29 questions linked to/from Expressions containing globally undefined symbols inside a function where they are defined
11
votes
4
answers
721
views
Using predefined expressions as free variables in a pure function [duplicate]
I want to have a function value of an expression where some variables are solutions to some set of equations, with some values of parameters. I had an idea to use pure functions for that.
However, ...
2
votes
3
answers
167
views
Globally Defining a Variable that Depends on Arguments of Functions [duplicate]
I have many delayed-defined functions of many variables, and all the functions share a term containing some of these variables. Thus, I would like to just call the term ...
1
vote
3
answers
931
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 ...
0
votes
1
answer
1k
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 ...
1
vote
1
answer
154
views
Implementation of a recursive function [duplicate]
I have been trying to implement a recursive function, but still struggle. Here's what I have written:
...
1
vote
1
answer
155
views
Substitution in delayed evaluation function [duplicate]
I am trying to do the the following: precomputing an expression and then making a function out of it. It has to be delayed evalution, because some of the parameters are only known when the function is ...
3
votes
1
answer
91
views
Defining function [duplicate]
ver1 = 2 x
verf[x_] := ver1
verf[3]
Result : 2 x
Expected Result : 6
In the above code ...
0
votes
0
answers
40
views
Basic Question on function of $n$ when it shift to $n-1$ [duplicate]
This question is basic, but I do not know what is wrong.
Clear[a0,a]
a0=n;
a[n_]:=a0
But when I evaluate a[n-1] the output ...
50
votes
5
answers
3k
views
Enforcing correct variable bindings and avoiding renamings for conflicting variables in nested scoping constructs
Using global variables the following turns an "expression" into a Function:
expr = 2 x;
Function[x, Evaluate[expr]]
Of course ...
12
votes
2
answers
6k
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-...
7
votes
5
answers
659
views
What is the the proper way to define a function from an expression? [duplicate]
Say after some long computation we get an expression
expr=x^2
We do not know what the value of expr beforehand.
Now we want ...
7
votes
4
answers
2k
views
Delayed evaluation of assignment
I have a set of PDE's that depend on parameters. They depend on many parameters, but for simplicity we can here assume that they depend only on one, say a.
I want ...
4
votes
3
answers
546
views
Using Block with a list of variables
I have a list of variables
var={v1,v2};
which I want to protect/localize during a particular operation. I have decided that I want to use ...
3
votes
4
answers
1k
views
Passing a function as an argument to another function using the same variables
I define a function with two variables and an argumment which is a function of this two first variables.
For example the function Ttrho below (the two variables are T and Rho and pTt is a function of ...
3
votes
2
answers
268
views
Recursion doesn't happen any more or doesn't happen correctly if I store the recursive relationship in a variable first
I know the following code will form a recursion:
Clear["Global`*"]
u[i_, n_] := u[i - 1, n] + u[i, n - 1]
u[0, n_] := n
u[i_, 0] := i
u[2, 2]
(* => 8 *)
But ...
7
votes
2
answers
175
views
How to create Functions that have Compiled functions effectively
I'm about to build a package that will provide lots of simple functions. I want these functions to run as fast as possible when evaluating numerically but still provide symbolic results when needed. ...
0
votes
1
answer
294
views
What to use instead of ReplaceAll to replace a parameter with a number before the evaluation of an integral?
This is probably very simple but I don't see the solution now. Let us say I have a variable e defined as
e=n
ReplaceAll can subsitute n with value 3 using
...
2
votes
2
answers
168
views
Changing from parameter to variable in Mathematica
I'm having trouble defining a function where I previously treated a variable as a parameter. See the following example:
var := 2*a
f[a_] := var
Then ...
2
votes
2
answers
87
views
Issues Implementing Pure Function
Thanks in advance for any assistance you may be able to provide. I'm new to Mathematica and running into issues creating a usable function from the code seen below. For context, all of this code works ...
1
vote
1
answer
249
views
nonatomic expression expected when trying to sum of the integrals of two functions
newbie to MMA.
After computing the following two integrals:
...
1
vote
1
answer
159
views
Order of evaluation
I am having a hard time figuring this out:
( sample ) I have any matrix which can have an arbitrarily large dimension.
...
1
vote
0
answers
252
views
Problem in evaluating nested anonymous functions [duplicate]
It seems that I have found a bug (or a fundamental problem in the design of the programming language of Mathematica) with functions defined as rules.
Define the function g as g(1)=2 and g(2)=1. We can ...
2
votes
1
answer
90
views
Difference Between Set and Pattern in Mathematica
Ok, sorry if this is too basic, I'm somewhat new to Mathematica, but I keep making errors in my code because I'm not understanding the namespaces.
So this part I thought I understood.
...
0
votes
1
answer
89
views
Defining a function when the variables do not appear explicitly in the definition of the function
I am trying to take the curl of a vector field which is the a product of a scalar field (Psi) and a coordinate vector, {r,Theta,Phi}. After taking the curl I want to calculate the magnitude of the ...
2
votes
1
answer
64
views
Handling a list of variable assignments to be used with `With` [duplicate]
Is there a way to use With as follows?
variables := {a = 2, b = 3};
With[variables, a^b]
Desired output
...
3
votes
1
answer
95
views
Forcing variable substitution on delayed evaluation
Problem, the following snippet doesn't substitute vars
...
1
vote
1
answer
105
views
Unit conversion in a function using another function as an argument
My problem is related to the previous post Passing a function as an argument to another function using the same variables. I don't understand why in the following example the conversion of units does ...
2
votes
0
answers
101
views
Definition of a function using variables outside of the function [closed]
I would like to define a function using variables outside of the function.
For example,
g = x + y;
f[x_, y_] := g;
f[1, 2]
then, I hope to get 3 as the answer.
...
0
votes
0
answers
51
views
How to transfer the list of parameters values into With [duplicate]
In the following case:
With[{x=1,y=2},Print[x+y]]
the values of x and y are declared in ...