Questions on assigning and unassigning definitions to names that represent them, including issues raised by context and localization. Use tag [assignment] for issues relating to Set versus SetDelayed.

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2
votes
1answer
67 views

Is there a shorthand for Optional with Condition?

I have a recursive function that does some work to an object for a repeatedamount of times. ...
0
votes
1answer
70 views

Weird subscript name in output [duplicate]

One of my first times using mathematica, I'm getting a weird Subscript(1,0) output when I try to solve a derivative. What is going on and how can I fix this?
1
vote
1answer
138 views

Iteration convergence of Newton approximations

I am trying to determine for which initial values Newton's approximation of specific functions (EX: f(x)=x^2 -1)converge and to what numbers it will converge to. *Where Newton's approximations are ...
0
votes
1answer
57 views

Simplify huge output or using the output without showing it in full [closed]

I'm trying to solve a system of differential equations. It works fine but Mathematica creates a huge output, which, when shown in full, results in a file size about 100 mb. Using Simplify doesn't work ...
0
votes
1answer
142 views

Plotting Complex Numbers - Functions of Complex Numbers [duplicate]

So I have to generate a few different plots with z, where z is a complete number... z[x_, y_] := x + y*I F[z_] := (25*Pi*z*I)/(1 + 10*Pi*z*I) First, I need to ...
0
votes
1answer
56 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 ...
4
votes
1answer
183 views

How can I overload a function with multiple bracket-slots so f[a][b] and f[a] can coexist?

Maybe this is not even possible: I want to create a function f that can have two input brackets like: f[a_][b_:1]:= a*b and ...
0
votes
1answer
92 views

How to specify the domain of a variable?

How can I specify for every expression the domain of a variable without using assumptions everytime i have to simplify it?
9
votes
1answer
235 views

Context of localised (dynamic) symbols

When you localise a symbol with Module, the created unique symbol is usually in the current context. There seems to be an exception to this which has further ...
6
votes
1answer
259 views

Context “Unique to This Notebook” makes variables black even if they're not defined?

I'm trying to use this technique to keep variables separated between different notebooks. It seems to be working fine, except that variables turn black as soon as they are evaluated — any ideas why ...
8
votes
6answers
945 views

Using a built-in symbol as a variable

I want to produce a Mathematica Computable Document in which N appears as a variable in my formulae. But N is a reserved word in ...
2
votes
2answers
550 views

How to define a vector with automatically added symbolic elements with subscripts

I want to define a vector lets say k containing elements Symbolize[Subscript[k, 1]], k2, k3 ... etc. When I define lets say k4 . I want the symbol automatically added to vector k. Something like ...
11
votes
1answer
183 views

Copy Built-in function to new name

It is know that some built-in functions are system function and changing their properties may cause trouble. Suppose for example I want to change features of Cases: ...
0
votes
0answers
15 views

Use of placeholders in functions [duplicate]

I'm having some trouble with Mathematica's placeholders within functions. The function sel[lowerLimit_] should select all elements of x that are greater than the lowerLimit: ...
10
votes
2answers
303 views

Another difference between Set and Setdelayed. Evaluation shortcut?

A little while ago I wondered why f[x_] = f[x] gives an infinite iteration. I ended up discovering the following difference in evaluation between ...
9
votes
2answers
342 views

Using up-values and down-values

I have a problem I'm trying hard to find a solution for, although I don't know if a solution exists. The following rules produce the result e[2].f[] ...
2
votes
0answers
25 views

Determining default value from previous arguments [duplicate]

How does one specify a default value for an argument which is dependent on the previous arguments of a function? For instance, consider the function ...
23
votes
4answers
2k views

how to differentiate formally?

I have been wrapping my head around this for a while now and I have not found a solution so far. I want to work with an arbitrary number of variables in mathematica and use some built in functions. ...
2
votes
1answer
105 views

Table of references [duplicate]

I have a list of variables (say a, b, c, d, e) that I want to assign in a single command. {a,b,c,d,e} = {1,2,3,4,5} would ...
0
votes
0answers
89 views

Numerical Integration/Function

I have a problem with a function defined numerically through an integral of the form: ...
11
votes
3answers
250 views

Find all heads a function is defined on

So say I've got a function g defined as follows: g[x_Integer] := x + 1 g[s_String] := s <> "!!!" How would I write a ...
17
votes
4answers
1k views

Elegant manipulation of the variables list

I have a list of global variables (some of them are indexed variables), for example: varsH = Hold[U0[1], U0[2], B0, V0[1], V0[2]] Or (if it is easier to handle) ...
-7
votes
2answers
143 views

Module function corrupts string? [closed]

I have the module who should replace some elements of a matrix with checkboxes ...
0
votes
1answer
75 views

How to assign the array data to variables?

A very basic question but puzzled me for long time on how to assign array to variables. For instance, we have array {{t1,x1},{t2,x2}...{tn,xn}} how to assign the first element to variable t and ...
20
votes
2answers
3k views

How to define a global variable when giving each notebook its own Context?

I have restricted the context of my notebooks to each individual notebook. So variables in each notebook are local and are not seen in another notebook. But in two of my notebooks I have two ...
6
votes
2answers
148 views

Injecting list of controls into manipulate

I am trying to program a method to manually move around graph vertices, and then output the new coordinates. I'd like to turn this into a function that can be called with a variable number of ...
4
votes
2answers
5k views

How to tell Mathematica that certain variables are real/imaginary, integer-valued, etc

I'm trying to expedite some quantum mechanical calculations by running them through Mathematica. Expectation values and stuff like that. When I say, for example, ...
0
votes
1answer
29 views

Variable as Difference of 2 Variables

I would like to evaluate a function based on the absolute difference of two variables. An example: g=5*x-5*x*y-5*y diff=x-y D[g,x] D[g,y] D[g,diff] I cannot find ...
3
votes
1answer
90 views

Defining a function that prints both the name and value of a variable defined locally within the calling function

To save time when debugging with Print statements, I'd like to define a function -- call it PrintVal -- that prints both the name and value of a variable defined locally within the calling function. ...
1
vote
1answer
90 views

How to form a variable from matrix elements

I have matrix with n rows and 2 columns, say m = {{x11, y12}, {x21, y22}, ..., {xn1, yn2}. Now, I want to form three new variables for example: ...
1
vote
0answers
116 views

How to create a complex variable from dated list values

Can anyone help me to construct a variable "PI" from values of variable x. Variable x represents a group of two time series rj and ri on equal dates(joined two dated lists with states).Variable x have ...
13
votes
1answer
320 views

Is garbage collection broken in version 10.0.0?

Bug introduced in 10.0.0 and fixed in 10.0.1 In version 10.0.0 under Windows I am observing the following behavior: ...
30
votes
2answers
1k views

Best practice of passing a large number of parameters to functions

I have a number of functions that all take a large number of parameters. I am wondering what is the best practice of passing these parameters to those functions. I could, of course, simply specify ...
2
votes
1answer
128 views

Equivalent command to the Maple indets command

This carries on the discussion here and here. I had mistaken Variable[] to give you ALL variables in an expression, but apparently, it is not meant for that. ...
0
votes
1answer
119 views

About Symbolize and Variables

I do believe this sort of similar questions had been asked many times, so I have read a LOT. For example this and this as well as many other related posts. But a glance at what my main question is ...
3
votes
1answer
101 views

Need some explanation of “Global`*”

When I start a new notebook, I enter Names["Global`*"] I get this {"list", "msgs", "rhs", "z"} Then I enter, ...
0
votes
2answers
118 views

Variable Value as Range

Thank you for the help so far! I would like to assign +/i signs for the function and solution such as (+)(+)(-) and therefore (-). It is working for the first evaluation, λlower, but not for the ...
3
votes
2answers
176 views

Convert matrix rows into variables

Can anyone show me how to set all matrix rows to variables. For example, I have matrix w={{1,2,3},{3,2,1},{0,0,0}} and I need to set each matrix row to be separate ...
5
votes
3answers
873 views

Assign output of solve to variables [duplicate]

I have this input: Solve[x^2 + 3 x + 2 == 0, x] which gives this output: {{x -> -2}, {x -> -1}} I want the first x ...
2
votes
2answers
175 views

Local variables whose definitions depend on each other [duplicate]

Consider the following (pseudo-)function definition: f[l_] := Let[{ a = Length[l], b = First[l], c = b/a, }, c*10] So for ...
1
vote
3answers
82 views

Store matched variables

Edit: I am matching and replacing a particular expression. At the same time... I want to store matched variables for later use. I got it to work with messed up code involving ...
1
vote
1answer
200 views

Solving equations with QuantityVariable

I'm trying to understand how to easily solve equations that use QuantityVariable. Why does this fail? ...
0
votes
1answer
35 views
0
votes
1answer
42 views

Reducing Output length by introducing new variables [duplicate]

I have outputs like "expression/(1+3*c^2) +anotherexpression/(1+3*c^2)" and so on. Is there any way to set 1/(1+3*c^2)=A where A is a new variable so that the output reads like ...
1
vote
0answers
272 views

specifying a list (vector) of arbitrary length

When trying to do symbolic calculations in mathematica involving a space of dimension n, which is arbitrary but fixed, I'd often like to work with vectors that have ...
4
votes
1answer
121 views
4
votes
1answer
151 views

Multiple down-values with exactly the same lefthand side

I was working on an answer to this question, when I was sidetracked by what I bring up here. I wanted a function, which when given a string representing a binary number, would convert the string to a ...
1
vote
2answers
106 views

Using AddTo in a function

I want to create a function that will take a variable $x$ and reassign the value $x+2$ to $x$. So f[x_]:= x += 2 However: ...
0
votes
3answers
169 views

Identifying the symbol which has a specific value

I'm writing a program that will solve the value of 1 variable in a 4-variable equality equation, but the variable to be solved will depend on the user's input to the program. This is what I've come ...