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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1answer
67 views

Defining functions that depend upon other functions which depend upon other functions and so on

The problem is that I have to evaluate functions, that take output from previous functions, and combine them to form new functions, and do some operations and evaluate the value at new function. But, ...
6
votes
3answers
316 views

How can I create currying functions using pure function syntax?

For example how can I write In: pureFunctionSyntax[myF] /@ {7, 3} Out: {myF[7, Log[7]], myF[3, Log[3]]}
3
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1answer
85 views

InverseFunction: how can I extract the function inside?

This is probably a trivial question. But I could not find an answer. Given the explicit expression for ft in te assignment ...
6
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1answer
362 views

What does it mean when a function is defined with two pairs of brackets

I have noticed a function defined as such: f[x_][y_] := expr; How is the argument y in 2nd pair of brackets being used? What is the difference from defining a ...
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0answers
50 views

Mapping over two indices with a condition

How can I use Map over two indices with a condition? I am trying to calculate second derivative of an eigenvalue, $\lambda_i(x)$, of $n \times n$ matrix $M(x)$ ...
5
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2answers
188 views

Getting Arg[z] to go from $0$ to $2\pi$

I'm defining branch cut functions, and I'm using $\arg(z)$ as a building block. So I just spent an hour at the whiteboard assuming that $\arg(z)$ goes from $0$ to $2\pi$, and then I implement the code,...
4
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3answers
140 views

List of functions to list of parameters

I am working in a Dataset and I need to create a function for a ChartStyle option of a ...
2
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1answer
102 views

Why must I specify the Global context for a symbol in a private package?

I have written two versions of the function below in a package. When I load the package and call the function, Why does the first version where the variable s has no explicit Context return the long ...
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0answers
51 views

Piecewise in 2D with quadrants as conditions

I am trying to define a piecewise vector field. Can the condition be of the form I am using (i.e. a quadrant)? I can't also make Piecewise work with more than two ...
6
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4answers
241 views

Recursive piecewise integral relation with piecewise base case?

How is this recursive formula $$ f_{n+1}(z) = \int_0^1 f_{n}(z-y)\,{\rm d}y $$ implemented in Mathematica? The base case is $$ f_1(z) = \begin{cases} 1 & 0\leq z\leq 1 \\ 0 & \text{...
4
votes
2answers
81 views

Assigning function values in a memoized recursive module

I have a complicated recursive module which I have memoized. I realised that certain isomorphs of inputs to this function will give the same output. Therefore I decided to memoize all such input-...
3
votes
1answer
64 views

Prevent expression from evaluation in function when using `ToString `

I defined function fhold Clear[fhold] SetAttributes[fhold, HoldAll] fhold[para_List] := ToString[para]; What I want is that ...
2
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1answer
121 views

How to properly define this function of function

I encountered real problem at first, and here is the toy example variable argument stored some expression that is generated from other parts of the program. I ...
9
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1answer
150 views

Why there is only `HoldFirst` but no `HoldSecond`, `HoldThird`, …`HoldN`?

I feel that this must be a duplicate. But I just can't find such a post. Mathematica has HoldFirst, HoldRest, ...
2
votes
0answers
68 views

Automating game simulation, using previous results [closed]

Based on this question on MSE, I would like to simulate a game whereby player $2$ enters a number, so as to test the strategy. The basis for this is the factor game online here. ...
3
votes
1answer
107 views

How to get name of “named row” in Dataset for function applied to each row

After some calculations and a GroupBy I have a Dataset that is structured like this. ...
4
votes
1answer
214 views

How to tame the wild MMA?

MMA is a free country. But TOO free sometimes. Just as an example: Clear[a] a[x_] == a[y_] ^:= Round[x] == Round[y] {a[3] == a[3.01], a[3] == a[4]} is {True, ...
3
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0answers
55 views

Memoized function with function parameter [duplicate]

I have some code that takes a function and uses the function to do some complicated computation. Thus, I wish to store this so I don't have to repeat this. Below, it is more simple than my real ...
1
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1answer
144 views

How to find period of a discrete sequence?

For example, {1,2,3,4,5,6,7,8} has period 1, the base is {1} {1,2,4,5,7,8,10,11} has period 3, the base is {1,2} I ...
3
votes
1answer
58 views

Setting a One Dimensional Function Equal to a Constant over a Specific Range

I am trying to take the output from NDSolve and create a variable equal to the solution except for a certain range of values. Here is the code I am trying to use ...
9
votes
2answers
227 views

How to assemble and disassemble a function into steps

I've watched many programmers (both novice and expert) write functions in Mathematica and have observed a common behavioral pattern. This pattern has many elements that would be automated and thus ...
0
votes
1answer
484 views

A problem with functions and Infinite expression 1/0 encountering

Following code (function) makes integrals and then replace f[x] with Cos functions and calculate the definite parametric ...
1
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3answers
306 views

Defining a function as a sum of several Gaussians

I have a function that is a summation of several Gaussians. Working with a 1D Gaussian here, there are 3 variables for each Gaussian: A, ...
1
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1answer
92 views

How can I avoid a scoping problem when differentiating?

I simplify my real problem as follows: I define a rule function as Clear[rule]; rule[i_] := tt -> i; the real rule function is not this simple. I define a ...
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1answer
150 views
10
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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
0answers
49 views

Improving numerical stability of the Goldstein-Price Function

Goldstein-Price Function is a two-dimensional test function for optimization, defined as $$f(y,z) = \left(\left(3 y^2+2 y (3 z-7)+z (3 z-14)+19\right) (y+z+1)^2+1\right) \times \left(\left(12 y^2-4 y (...
2
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2answers
76 views

Plot does not take range with OptionValue and PlotRange option

I am making a function that is to use Show to overlay a few plots of a function. I want the first Plot in ...
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: ...
1
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1answer
103 views

How to write or extend operators like $*\!\!*$

I'm stuck on trying to define simplification rules for NonCommutativeMultiply, much like ExpandNCM found in Documentation Center, under Applications. For example, I'd like ...
3
votes
2answers
202 views

Pollard's Rho algorithm

I'm working in Mathematica and I'm trying to implement the [Pollard's Rho Algorithm for the Discrete Logartihm Problem][1].
0
votes
1answer
41 views

Construct a function whose definition depends on the values of its arguments and evaluates a Section

I have defined a function that returns different output according to the values of the axes of an ellipsoidal. If none of the Which statement cases is satisfied then the function evaluates the ...
6
votes
1answer
128 views
2
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1answer
51 views

Defining function [duplicate]

ver1 = 2 x verf[x_] := ver1 verf[3] Result : 2 x Expected Result : 6 In the above code ...
1
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1answer
26 views

Evaluate function entrywise on high dimensional array [closed]

I have defined a function $f$ from number to number. I want to tell Mathematica to apply that function to each entry of a high dimensional array $A$, to get a new array $f(A)$ in the same form of $A$. ...
1
vote
1answer
81 views

Defining function from table [closed]

I have a table of values of the form Table[{i1,j1}, {i2,j2}...] and I want to define a function like f[i] to take the values ...
5
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0answers
79 views
4
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3answers
232 views

How to tell Mathematica that the argument of a function is real?

I want to define the following function in mathematica: $$R(\psi)=\begin{bmatrix}1&0&0\\0&\cos 2\psi & \sin 2\psi\\0&-\sin 2\psi & \cos 2\psi\end{bmatrix}\qquad,\psi\in\mathbb ...
9
votes
1answer
332 views

Two identical functions give different answers

I am new to mathematica and I hope this is a simple problem. I have two identical functions that only differ by the variable names: ...
1
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2answers
58 views

Find function to relate two lists of values

I know Mathematica has the FindFit function to determine the parameters of a known function that fits a sequence of points, but what if you do not know the relationship (linear, log, quadratic, etc)? ...
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 ...
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 ...
2
votes
1answer
188 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
345 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 (...
8
votes
2answers
183 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: ...
21
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2answers
363 views

Kernel inexplicably hangs if I define a pure function without suppressing output

Bug introduced in 9.0 and fixed in 10.0.2 Save any unsaved work before trying as it may crash Mathematica and other programs by filling up the memory! In v9.0.1.0 on OSX 10.8.5, if I start a new ...
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}{\...
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 ...