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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6
votes
1answer
99 views

How to delay the definition of a function from the time of package initialization to when it is first called

I am writing a package where a couple defined functions take a very long time define at initialization time (because they are large CompiledFunctions). However ...
2
votes
1answer
190 views

How to define functions with a list of arguments

I wante to define several functions, all of them with the same arguments, for example: f[a_, b_, c_]:= ... g[a_, b_, c_]:= ... h[a_, b_, c_]:= ... How can I do ...
1
vote
1answer
348 views

How to define a periodic function from an interval to Play (monotonic) sound

I would like to define a function on an interval and then duplicate it on other intervals of the same length in order to define a (generally discontinuous) periodic function, from which I could get a (...
3
votes
1answer
130 views

Programming a MaxMin Linear Optimization

I want to program a function for a two-player game. Basically it's like this: . Each player has an array of options, and the result of the game is based on both players choices. So heres my most ...
8
votes
2answers
184 views

Name rewriting for Function fails in closure

At its heart, Mathematica is a dynamically scoped language. While the choice of dynamic scope for Mathematica is very much a defensible one, lexical scope is too useful to do without, and Mathematica ...
1
vote
4answers
206 views

How to define a conditioned function that returns one when x is integer and zero otherwise? [closed]

What is the simplest way to define a conditioned function that returns one when x is integer and zero otherwise? I'm doing it wrong: ...
3
votes
1answer
73 views

Using functionals in Mathematica [duplicate]

I recently installed Mathematica and I wanted to define a functional in it. This is what I did: ...
15
votes
4answers
434 views

Skipping “middle” Optional Arguments

Is there a way to call a function where the "middle" arguments should use their default value while specifying values for the "right-most" arguments? For example, given this function: ...
4
votes
1answer
67 views

Create a function for $\Pi^{-1}(n)$

Is it possible to create a function that gives the inverse of pP[x_] := Sum[PrimePi[x^(1/k)]/k, {k, 1, Floor[Log2[x]]}] i.e., a function that plots ...
0
votes
1answer
50 views

Checking the solution of a differential equation with a boundary condition depending on an arbitrary function

I have the partial differential equation: $\qquad U_{x} - 4 x^{2} U_{t} = x U, \qquad U(x,0)=f(x), \qquad x \in (- \infty, \infty), \qquad t \in (0, \infty)$ Where $U_{x} = \frac{\partial U}{\...
6
votes
2answers
356 views

Calculating extreme spread with a Do loop [closed]

I am trying to model what is called the extreme spread of a series of shots at a target. Each shot is from a normal distribution with mean 0 and variance 1. For this example there are three shots per ...
16
votes
3answers
287 views

Is it possible to change the order that symbol definitions are checked? (DownValues vs UpValues)

Suppose I have the function f with the following definition assigned to it: ...
6
votes
2answers
287 views

What evaluation mechanism is behind Mathematica support for multiple definitions of a function? What is the benefit of this?

I am studying the question What are the most common pitfalls awaiting new users? Up to now, I have fulfilled some of the parts but yet don't understand which this problem is related to? Consider the ...
10
votes
1answer
240 views

Question about Rules and Pattern (The operator patt/;test)

Maybe this question is so trivial but it has confused me. I'm studying the What the @#%^&*?! do all those funny signs mean? and in the Rules and patterns under ...
0
votes
1answer
91 views

Optimization of a voxel projection function

I implemented a function to check if a voxel (3D pixel) is well projected on the space of a image (black and white silhouette) through a perspective camera. The function does the work but It need more ...
2
votes
3answers
198 views

data manipulation in log-log scale

Say that I have the following: y[t_] := 2 + (2/10)*(1 - Exp[-t/11]) timedat = N[Table[{t, y[t]}, {t, 0, 10, 1/1000}]]; How is it possible to construct an ...
4
votes
2answers
109 views

Unsure how to nest / fold this power tower factorisation

Not quite sure how to nest this. What I would like is power tower of integer factored until all powers are primes. eg desired output for f[3*125^4] would be ...
0
votes
1answer
70 views

a function that evaluates a Section

I have defined a function that returns different output according to the values of the axes of an ellipsoidal. The function is given below: ...
2
votes
0answers
36 views

Unexpected behavior from Return called in a Block [duplicate]

I like to write functions that dispose of failure cases early, before they do the main calculation, but I don't like to write cascading If statements. Here is a toy ...
1
vote
1answer
70 views

Writing a function with two functions as arguments

I am trying to write a function of two functions. A function of one function works as in h[f___, x_, y_] := Integrate[f, x] h[x^2 + y, x, y] and this ...
2
votes
3answers
98 views

Making a list of functions

Suppose I have the following equation system to solve: x(t_):={x1(t),x2(t)}; DSolve[x'(t)==x(t),x(t),t] This code works fine, but now suppose that instead of 2 ...
9
votes
1answer
178 views

Finding large prime gaps

I am using basic searches for prime gaps as follows: ...
19
votes
5answers
367 views

Distributing function arguments with function compositions. How to compute $(f + g^2)(x) = f(x) + g(x)^2$?

Suppose I have two functions f and g. To compute $f + g$ evaluated at a point $x$, I know that one can use ...
0
votes
1answer
79 views

Working with functionals [closed]

I am trying to work with functionals in Mathematica, this means that I want to define a function of a function. I defined my function of a function as: ...
1
vote
2answers
54 views

Replace function with multiple functions while respecting the inputs

I want to replace a function with either one or two functions and also combine their arguments. Say I have an original expression expr = u[i + 1] r[i] r[i-1] ...
3
votes
5answers
307 views

Function involving For loop

I've written the following function (the code includes the output): ...
1
vote
1answer
107 views
17
votes
3answers
473 views

Improving speed of code computing number of nonrepeating partitions

I need to answer the following for a number of parameters: How many ways can the integer $k$ be written as a sum of $n$ different integers ranging from $1$ to $m$? My initial attempt was the ...
0
votes
0answers
56 views

Is there a IsDefinedQ function? [duplicate]

I have a function which is a bit expensive to calculate. I want to translate and integrate. I want to translate by values on a grid, store the values of the integral and refine the grid. That is, I ...
2
votes
1answer
68 views

How can an argument of the form f[t] be injected into the RHS of a function definition [duplicate]

This is what I want, for an arbitrary function x This is what I have done: ...
6
votes
2answers
158 views

How to specify and use nested options for a function?

I want to write a function that takes options that are nested. For example, suppose the function has one main option, "method" which can take two values, "a" and "b". Also, when method is "a", it can ...
4
votes
2answers
248 views

Generate the Fibonacci sequence with Accumulate

Is there a way to generate the Fibonacci sequence with the Accumulate function?
6
votes
2answers
119 views

Force evaluation of the right-hand side of a local variable definition

One can do expression = a + 1; f[a_] := Evaluate[expression] but how would one do something like this ...
-1
votes
4answers
107 views

Converting an expression to function [duplicate]

I have the following problem. I current can automatically create the variable positionPayload, for instance: ...
0
votes
1answer
115 views

Replacing the Slot in an expression

So I've got Mathematica to handle the grunt work for me to obtain expression: Root[ (* blah, blah *) + #^2 + (* etc, etc *) ] Now, the value inside Root is a ...
4
votes
1answer
124 views

Substitute a function's definition for its name

I'm having trouble with a function which is supposed to work on another function. Simplified version: ...
3
votes
2answers
78 views

How can I adjust the global input variable of a function to the value of a local variable within the function

I am trying to define a function f[l_] that will perform an operation on whatever input variable I use (normally I use l which ...
1
vote
2answers
55 views

How to define a function `deriv[f[x]]` such that its output is an unevaluated expression `fx=D[f[x],x]`?

I want to define a function deriv[f_[x_]] such that when I run deriv[f[x]], the output is an unevaluated expression ...
0
votes
2answers
62 views

Function to list Collatz sequence doesn`t work [duplicate]

I am new to Mathematica and was trying to make a function that lists the Collatz sequence stating with a given number, but I can´t get it to work. Here is my function: ...
1
vote
1answer
176 views

Defining a derivative on a custom function

I am trying to define a derivative that acts on a custom function, $f$, such that when it acts, it increments one of the arguments of by 1. f is not defined; I just want to use it to keep track of ...
2
votes
1answer
66 views

Dropping rational coefficients

I have a list of expressions (they all are exact numeric quantities, not containing any variables), some of them have integer or rationals coefficients, or complex coefficients with rational or ...
1
vote
3answers
125 views

Setting ::usage for variables returned from a function

What is the best way to achieve {v,u} = f[]; (* Returns value and usage description *) v::usage = u; from inside f, i.e., <...
2
votes
1answer
63 views

Manipulating unevaluated expressions in nested function calls

This is a follow-up to my earlier question: Passing an unevaluated part of an association to a function I'm trying to create a modular dashboard that controls sound volume of an audio system ...
0
votes
1answer
115 views

Element assignment in matrix function

I have to define a function of two variables that yields a high dimensional matrix, with each entry containing a scalar function, that uses its coordinates in the matrix as input. like this: ...
2
votes
1answer
251 views

How to get numerical results from HeavisideTheta?

I have defined a table tab = {7.52521, 17.0083, 22.5678, 11.8707, 8.27799} and a function ...
1
vote
1answer
105 views

Min function for functions f1, f2, [closed]

There are several "min" functions in Mathematica. In the "Numerical" category, there is a "Min" function that works on a numerical list. Then there's MinValue for finding the minimum of a whole ...
0
votes
0answers
40 views

Dot production associated with comparison process of different matrices eigenvectors

With thanks to Guess who in the link module using.. We created functional 5*5 matrices: ...
4
votes
1answer
148 views

How can you get the area of a region from an image?

Suppose we have a square of side "L" m, How can I calculate the hatched area, if the corners of the square are centers of circles. It can be generalized to any region? edit: This is the result I ...
22
votes
4answers
338 views

Is there a GraphicsPrimitiveQ (or a complete list of Heads of graphics primitives)?

For various reasons related to workflow associated with creating figures for journals, I am creating functions that will accept graphics primitives and a set of options and spit out a ...