Tagged Questions

For questions on writing functions (pure or using Set/SetDelayed) for any purpose, including the features that may be incorporated in those functions, such as options, patterns and conditions.

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2
votes
1answer
30 views

Mapping also for one element (or telling it how to do so if head got changed)

Some code generates a polynomial, and has the form: expr = Plus[a[i],b[i],c[i],d[i]] I need to apply f to each term. To do ...
1
vote
1answer
61 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
1answer
64 views

Plotting a function in {X(Y),Y} space

The code below generates some data and defines a function f[x,cb]:=NMaximize[expr,x] that upon being evaluated returns: {function value at max $x$,the function maximizing $x$}. ...
4
votes
1answer
64 views

How to track Part of Symbol or How to symbolize Parts of Symbol without copying data

Let's create simple function: SetAttributes[h, HoldFirst]; h[data_] := Dynamic[Grid[data], TrackedSymbols :> {data}] test = RandomReal[1, {2, 2}]; h[test] ...
5
votes
3answers
157 views

How to get “Signature” of each element of “Permutation” output

I need to sum over all possible permutations, multiplied by the Signature of each permutation of a given list of symbols. But, I don't know how to determine the ...
1
vote
0answers
82 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 ...
0
votes
0answers
32 views

Confusing memoization behavior — caching a function that returns a function [on hold]

Here is a simplified version of what I am trying to do: ...
1
vote
2answers
46 views

What is the correct syntax for using a radio button to set values to be used elsewhere? (restated)

Here is my question, restated - I want to be able to choose the values for a complicated function from a set of alternatives values that I have gathered. The function requires several input values, ...
2
votes
2answers
42 views

Returning the 3-dimensional vector from a skew symmetric matrix

I'm trying to write a function that takes in a skew symmetric matrix and returns the corresponding vector. When I write the following code, it works when I leave it as variables, but it does not work ...
0
votes
0answers
22 views

Add constraints to a variable number of parameter in Minimize

i want to use Minimize with a variable number of Parameter which works fine: ...
3
votes
2answers
53 views

Fast functional method for multiplying duplication numbers in a large list

Consider a list of symbols: mySet = {a, b, b, c, a, b, c, d}; I would like to form the product of duplication numbers. In the example above, I have 2 ...
-3
votes
0answers
24 views

generating a function wherein data are given

Good day! I would like to ask whether is it possible to generate a formula out of the given data..I believe that the data, when graph, form a Natural logarithm function but I dunno the exact ...
2
votes
1answer
42 views

Unprotect fails the first time, works on second pass [duplicate]

I am redefining some of the standard math functions. I know this is dangerous, so I am trying to be extra careful. (For instance, in the redefinitions, I make sure to only match a custom head) The ...
3
votes
2answers
88 views

How to define multiple functions using a for command

Let's say I want to plot 10 graphs of those following functions. Since they are recursive functions, I cant make a table with 10 different initial conditions because Mathematica stores each value ...
2
votes
3answers
135 views

Extracting coefficients from a power series

I have a function defined explicitly as a power series: $$\sum_{n=0}^\infty{T_n}\frac{x^n}{n!}=\frac{\frac{x^3}{3!}}{e^x-1-x-\frac{x^2}{2!}}$$ and I would like to extract the coefficients $T_k$ as ...
7
votes
2answers
102 views

using memoization with conditional statement

I would like some advice about the use of memoization in conjunction with conditional statements. Let me try to explain my problem: I am constructing a function depending on a number of parameters. ...
5
votes
3answers
73 views

Mapping a function of the form matrix[[row,column1;;column2]] over a list

I want to create a list of lists of values by mapping values[[row, col1;;col2]] over a list like {{r1,c1,c2},{r2,c2,c3},... } to ...
2
votes
1answer
46 views

defining Associated Stirling numbers of the Second Kind

First, I'm new to Mathematica. Spent my undergraduate programming with Maple and my computer crashed and I lost it. Fortunately, my university offers free Mathematica downloads to students, so here ...
6
votes
2answers
159 views

How to write complex function definitions at run time?

(Posting as a self-answered question to share a technique I discovered) In a certain project, I have many function definitions in which all parameters should be optional and come with default values. ...
13
votes
6answers
501 views

How can I evaluate only a single step of a recursive function?

Let's say have a simple recursive function for the Fibonacci sequence f[0] := 1 f[1] := 1 f[n_] := f[n - 1] + f[n - 2] but I want to see how it will expand in a ...
4
votes
3answers
150 views

How to re-parse (or re-map) character '.' to user-defined function

The default behavior of the character . between two non-numeric characters is to be interpreted as the infix of the Mathematica function ...
0
votes
1answer
35 views

Rigging a function to output a distinct value every nth call

There's some fixed script I am unable to alter (keeping things simple: Table[f[i], {i, 1, 10}]), , however, I can alter a function that the script calls (again, ...
2
votes
0answers
88 views

Oddify an even function and vice versa?

I want to know how to construct a function in Mathematica which would produce even analog of odd function and vice versa in closed form? The mathematical definitions are as follows: ...
0
votes
0answers
117 views

How to create a reliable natural integral operator? [duplicate]

Natural integral is one of the antiderivatives of a function, for which the integration conctant is fixed in a natural way. It is defined as follows: ...
-1
votes
2answers
62 views

Plot not showing values

Still pretty new too Mathematica. Can someone please point out what im doing wrong when trying to plot the Dijkstra' s fusc function? code: ...
3
votes
1answer
59 views

Function of arguments given in non-fixed order [duplicate]

normally we define functions as f[x_, y_, z_] := ArcSin[x^2*y/z] however when one has many arguments (as I do) I find difficult to remember what is the meaning ...
1
vote
0answers
39 views

Fine tuning compiled code that computes dilogarithm function

As an exercise of writing a good Compile function, I want to do the simple task of coding a routine that outputs the real part of the dilogarithm function ...
2
votes
3answers
58 views

Reconstructing an expression [duplicate]

I have a nested expression like this one expr = Tan[Sin[Cos[x]]]; I can deconstruct it with ...
1
vote
1answer
57 views

Code check: Force simplified inequalities to be of form `expr > 0`

Simplify is a nice fast function that cleans up simple inequalities. For example: ...
5
votes
2answers
224 views

Define a rule of derivative in NonCommutativeMultiply?

In tensor calculation, I need to do the following thing: Define a derivative operator Drv[fun,i], such that ...
0
votes
1answer
39 views

Changing default behavior of Series to give slightly different SeriesData

I am working with complicated expressions expr that contains the symbolic function f[x] which I know to have a pole at ...
7
votes
3answers
114 views

Defining a custom Plus for a specific class of arguments

I'm trying to develop an domain-specific language with Mathematica. I want to define a customized behavior for the Plus function when applied to my data. For ...
0
votes
2answers
82 views

How to get `Series` to recognize user-defined function has pole

Edit for clarity: How does Mathematica's function Series know that Gamma[x] has a pole at ...
5
votes
3answers
124 views

What is the recommended way to define numeric function with special cases?

What is the recommended way to define a purely numeric function with special cases? Should I define many special cases with pattern matching? ...
1
vote
2answers
42 views

Indeterminate result from function, but not from equivalent expression [closed]

Can anyone explain this result? Why is one result Indeterminate and the other not? ...
6
votes
5answers
385 views

Find function inverse

I'm trying to find the inverse of a function: (30*x^2 (1 - x)^2) (* where 0<x<1 *) I tried all the following options: 1. ...
3
votes
3answers
88 views

Defining a function that that evaluates a function to obtain a value not supplied as an optional argument

I have a function like this CentralDifferentMethod[α_, β_, α1_, α2_, λ_, v0_, dt_, t_] Now, I want to add a new parameter ...
2
votes
1answer
65 views

Using HoldFirst but not wishing to hold everything

I have a DynamicModule in which I go through some data analysis and keep or reject the results. Here is a toy example of what I am doing. ...
1
vote
1answer
87 views

Function returned an unexpected list

I was trying out a question in Wellin's Programming with Mathematica that says the following. Question: Given a set of points in the plane (or 3-space), find the maximum distance between any pair of ...
2
votes
0answers
59 views

How to make a new analytic function work seamlessly with Mathematica's analysis functions?

I am defining a new analytic function of six variables. I have algorithms to evaluate it numerically, and have amassed a large catalog of analytic properties. It is easy for me to program the ...
4
votes
0answers
156 views

Strange behaviour of MMA in derivatives of some standard functions

There are some peculiar things to be discovered in derivatives of some standard functions in MMA: Strange behaviour Example 1: Abs We have ...
3
votes
0answers
61 views

Listable on first level

I have some function which take List as input. f[l_List]:=someActions[l] I need apply this function to a list of lists. Now I ...
0
votes
1answer
46 views

Output a symbol from Module or Block

I have troubles to output an entire symbol, a function in this case, from a module or a block. For instance myf = Block[{f}, f[3] = 33; f[4] = 4; f] Then I want ...
1
vote
1answer
59 views

PDF for Normal-Gamma Mixture

The normal-gamma mixture is: ...
8
votes
2answers
172 views

Error computing sum of sum of digits

I've defined a function that computes the sum of the base-b digits of n: DigitSum[n_, b_] := Total[IntegerDigits[n, b]] Then I defined a function that computes ...
5
votes
2answers
127 views

How to understand the process of ListCorrelate when it in two-dimensional condition?

Toady,I learn a function ListCorrelate,and I can understand process of execution his result in one-dimensional. However,the ...
2
votes
2answers
84 views

How to make functions from datasets

I have a csv that encodes the results of plugging certain parameters (say, A and B) into certain functions (say, ...
1
vote
1answer
38 views

Specifying independence of a variable in a function

I am dealing with a function of a finite number of variables and among the operations I wish to do is to differentiate it repeatedly with respect with any of the variables. Now this function happens ...
2
votes
1answer
48 views

How do I tweak the input assistant to use string completion on my own functions? [duplicate]

I would like to be able to use Mathematica's string completion feature for subvalues of my own functions. I tend to go for functions that follow the pattern ...
1
vote
1answer
86 views

Passing function as argument

I've been mucking around with passing functions as arguments to other functions and via trial and error seem to have something that works. I was wondering if someone could have a quick look at some ...