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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1
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0answers
27 views

How to make Expand work right in a function definition?

This works just fine: Derivative[n_, 1][g][x_, v_] := D[g[x, v], {x, n + 2}]/2 + D[D[g[x, v], x]^2/2, {x, n}]; h = Expand[D[g[x, v], {v, 3}]] I would like to ...
6
votes
1answer
184 views

Parentheses for negative integers

Trying to standard create prime factors presentation, but can't seem to remove the parentheses: ...
1
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1answer
186 views

How can I call the R-programming packages in my Mathematica?

I am trying to call the R-programming package called highfrequency in my Mathematica so that I can use its function rCov. I ...
3
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1answer
42 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
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1answer
80 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
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1answer
72 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 $x$}. ...
6
votes
1answer
101 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] ...
6
votes
3answers
180 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
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0answers
100 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 ...
1
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2answers
60 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
59 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
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0answers
53 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
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2answers
60 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 ...
2
votes
1answer
49 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
105 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
174 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
116 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
85 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
77 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
189 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. ...
14
votes
6answers
555 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
180 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
36 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
102 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
118 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
67 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
66 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 ...
2
votes
0answers
47 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
62 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
65 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
247 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 ...
1
vote
1answer
77 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 ...
8
votes
3answers
120 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 ...
2
votes
2answers
94 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
129 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
46 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
495 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
89 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
72 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
91 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
68 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 ...
5
votes
0answers
177 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
66 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
49 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
64 views

PDF for Normal-Gamma Mixture

The normal-gamma mixture is: ...
8
votes
2answers
183 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
149 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
91 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
44 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
53 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 ...