Questions tagged [variable-definitions]

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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Numeric integration with symbolic boundaries

The following is a definition of a numeric integration: ...
55 views

Part of array as a blank variable [duplicate]

I have a little question. Let me define the function: f[k_]:=k So 'k' in the argument of 'f' is a blank variable. Is there a way to define a part of array as a ...
54 views

Errors appear after integration of an interpolating function

I have a little question about integration of an interpolating function. There is an error in assumptions of the integral. I have a function that was obtained with an interpolation method: ...
77 views

Plot implicit function with intermediate variable

Cross-posted in Wolfram Community. Here, I intend to plot a 3D picture of with two implicit functions where $x, y, t, \xi, \eta$, are variables. Of course, these variables can be constrained to ...
54 views

Numerical integration in one variable, of a multivariable interpolation function

I create the following set of data: newmatrix = Flatten[Table[{t, v, new[t, v]}, {t, 0, 2 Pi, Pi/4}, {v, 0, 1, 0.01}], 1] where ...
65 views

expression evaluation for Compile[] too time consuming

I need to use Compile[] for a very large expression to be integrated. But for Compile[] the expression has to be evaluated, and this takes endless time. The expression is composed of several functions ...
83 views

Problems with TagSet

I am new with TagSet and TagSetDelayed and I'm not understanding properly how they works. I introduced the following definition: ...
43 views

Is always possible to define a numerical value using subscript?

In this code I defined some values using subscripts and it is not the first time I did this but strangely the code execution crashes. To follow the code. ...
136 views

Making a list of variables

Consider the following code, which give a Manipulate object that returns the "total" of a certain variable var 1 ...
67 views

Remembering function definitions across sessions to avoid recalculation [duplicate]

I'm working with some large expressions and fourier transforms, which usually take a long time to compute. When I save my notebook with outputs to all my inputs, I'd like it to remember those ...
45 views

Defining a function expression [duplicate]

I'm sure this has been answered before, but imagine I have the following function ...
45 views

Matching two lists and create variables

I have two lists of the same length. One of the lists has all the variable-names in it and the other one is a list of lists in which each list represents a value. I now want to automatically create as ...
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Define variables dynamically to compute a function

Let's say I have defined a function $W(p, q)$, where $p$ and $q$ are integers between (and including) $0$ and $2$ and the function takes me to a real number. Upon an input $n$, where $n$ is a positive ...
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Plot SinglePredictionBands associated with a FittedModel (e.g. LinearModelFit) that is supplied as a variable

I am puzzled about how to plot the SinglePredictionBands associated with a FittedModel (e.g. ...
59 views

Overwrite a tensor product notation a_\[TensorProduct]b_ := KroneckerProduct[a, b]

I noticed that the definition of KroneckerProduct and For example TensorProduct[({ {0, 1}, {1, 0} }), ({ {0, 1}, {1, 0} })] Output: {{{{0,0},{0,0}}...
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user-defined functions and "pattern" being returned [closed]

I define a function as f[J_] := Exp[J^2/2\[Mu]] but when I try to taylor expand as k[J_] = Series[f[J] ,{J,0,2}] I'm getting ...
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Creating new variable names, Symbol or ToExpression

One can create new variable names by Symbol : In Table[Symbol["x"<>ToString[i]], {i,1,5}] Out {x1,x2,x3,x4,x5} But it is also possible to ...
51 views

a variable as all values from a list

I have a small Problem with lists and variables. I want mathematica to calculate a formula I derived for 200 values of w between 0 and 5 in ascending order. (maybe I can define w along the lines of) <...
67 views

Dynamic updating problem

Consider the code ...
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Suppose you want to access a variable defined in a "surrounding" context (scoped via Begin and End) from within ...
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Why does f[set_]:=AppendTo[set,5] not work when applying f to a set?

The following code works ccc = {}; AppendTo[ccc, 5]; ccc and gives the output {5} However, the following code does not work: <...
143 views

Construct 1 variable function from given 2 variable function

Given a function f[x , y]. The definition of f is not self-describing. (f was defined with objects other than f.) Then I want to construct a function g[x] such that f[x,y] and g[x][y] are the same, ...
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Certain plotting functions are setting variables unwantedly

I came across the following problem. Certain plotting functions set variables to values, which I do not want. For example, if I run SliceVectorPlot3D with an ...
51 views

Redefining the output of a function

ftn1 = Sin[s]^2 + 3 t^2 + u^5 3 t^2 + u^5 + sin[s]^2 ftn2[s_, t_, u_] := ftn1 ftn2[2, 1, 2] 3 t^2 + u^5 + Sin[s]^2 Hi ...
71 views

Display assumptions of a variable

If I restrict a variable x to x>0 via \$Assumptions=x>0, is there a way I can get ...
69 views

Passing symbols, variables and defining functions within functions

Moderators state: “You will be brief and straight to the point”, and so do I. All codes test whether a polynomial is even or odd, using different approaches. This works: ...
138 views

Function incorrectly renaming variables in Rule Pattern

Consider the simple pure Function containing a Rule with the named pattern q. ...
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evaluating some of the same variables inside a function while some of them are declared beforehand

This is a style question I suppose, not sure. Ok so I have this: a := RandomInteger[{1, 10}]; f[a_] := a - a f[a] ...
55 views

Proper way to construct a function that takes too long to plot and integrate

Consider the functions phi[t_] and psi[t_] defined in the code below. These are used as basis functions for interpolation ...
119 views

'Do' loop acting on a global variable

I need a code that will allow me to alter a matrix (a global variable) iteratively using a function update (which depends on ...
33 views

Variables with super/sub scripts

So I know how to create variable names with subscripts/superscripts at the end (using ctrl+_ etc), however, how would I use them in the middle of a variable name?
79 views

Issue with several replacements in a function under certain conditions

I am trying to define a function (reduce[x]) which does several substitutions, depending on the values of certain parameters. Concretely, consider an expression x, which contains an arbitrary number ...
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Define/store individual elements of Table output for back-substitution

At its core, mine is a very simple communication error between me and Mathematica that I haven't been able to crack, so I do apologise if it seems embarassingly inane. Please consider the following ...
54 views

Getting error messages form Set while trying to implement the bisection method with a For-loop [duplicate]

My objective is to build a function using modules that runs the bisection method. I have a working bisection method but when I try to implement it as a module I keep getting this error and I can't ...