# 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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### 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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### 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 $M(x)$ ...
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### 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 ...
137 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 ...
92 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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### 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 ...
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### 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 ...
420 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: ...
101 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 ...
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### How to build a function object like the built-ins such as Interpolation?

There are many built-in functions that return a function object, such as Interpolation[], BSplineFunction[] ,...
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### 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].
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### 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 ...
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### Is there an elegant way of delaying evaluation of A==B when calling a function that uses this pattern

Suppose I wanted to define a number of functions that accepts expressions of the form: ...
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### Defining function [duplicate]

ver1 = 2 x verf[x_] := ver1 verf[3] Result : 2 x Expected Result : 6 In the above code ...
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### 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 $A$. ...
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### 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 ...
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### Does Compilation option “InlineExternalDefinitions”/“InlineCompiledFunctions” lead to unnecessarily complicated nesting?

Question: When an external (possibly complicated) definition f is used inside a compiled function with ...
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### 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 ...
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### 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: ...
54 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)? ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
163 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 ...
204 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: ...
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### Using functionals in Mathematica [duplicate]

I recently installed Mathematica and I wanted to define a functional in it. This is what I did: ...
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### 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 ...
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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 $U_{x} = \frac{\partial ... 1answer 66 views ### Create a function for$\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 ...