# Tagged Questions

Questions about the use of built-in Mathematica functions, including pure functions.

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### Greater operator should give greater element

4>3 gives True. What is the "greater_operator" to obtain the result 4? For lists accordingly: ...
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### Defining a function to use in another function dependent on similar parameters [closed]

I want to define a variable dependent function which can be used to define another function which depends on the same variable and other variables. For example, I have a system where I define ...
75 views

### FindRoot, How to Return Null After x Number of Iterations

I am using FindRoot to find the root of a function, say f(x), and going through a loop for different values of ...
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### How to implement the for loop to replace text strings or texts?

I wonder define a bunch variables named like $X_1$, $X_2$, $...$, $X_n$. Is there some smart way to declare them instead of by pure typing. One trick I can image is to use the for loop,...
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### Cannot assign one element of an multi-output function (a list of outputs) to a new function

My aim is to define two functions by writing only one time the actual definition. The first one gives me a matrix and the second one is one of the elements of the matrix. Moreover, as I want to ...
383 views

### DumpSave 10.2 style from 10.3

Szabolcs has asked WRI support about mx files, in particular: Can we expect that MX files written by Mathematica 10.0.0 will be readable by future point released such as 10.0.1 or 10.0.2? ...
107 views

### Relevant help page for: Sum?

When I type Sum into Mathematica, it also offers Sum in the autocomplete dropdown, but when I click the little menu button next ...
191 views

### Defining Function With Two Variables [closed]

I need to define some functions with more than one variable, but the examples only list one variable cases, so I tried this: f[x_, y_] = (y/x) + xy f[1, 2] ...
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### What has changed in the Template system in 10.3?

Bug introduced in 10.3 and persisting through 10.4.1 There are couple of issues that are breaking my code after upgrading to 10.3. I wasn't able to narrow all of them down but this is what I've ...
248 views

### Vertex descendants subgraph

Keywords: vertex, ancestors, descendants, subgraph, directed graph, flow subtree So let's say we have a TreeGraph: ...
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### How to instruct MatrixLog to work with singular matrices?

How to instruct MatrixLog to work with singular matrices by ignoring the zero eigenvalues (thus only acting on a subspace orthogonal to the matrix kernel)? I'm ...
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### How can evaluate this function [duplicate]

Suppose this function F[c_, n_, s_] := Module[{}, Abs[s - 1 + (-1 + c)^n]] I calculate its second derivative on c ...
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### Composing multiple functions [closed]

I am trying to compose three functions in the following manner: Adx[z_] = (z[x + dx, t] + z[x, t])/2 Ddt[z_] = (z[x, t + dt] - z[x, t])/dt Ddt[Adx[z]] I get the ...
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### Why Chop does not make the real part of machine complex numbers an exact zero? [duplicate]

The documentation says Chop does not make the real part of machine complex numbers an exact zero: In[2]:= Chop[10.^-12 + 2. I] Out[2]= 0. + 2. I Why does ...
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### Map a function of several arguments

I have three lists, e.g. list1 = {{a,b,...}}; list2 = {{1,2},{3,4},...}; list3 = {{x,y},{z,w},...}; and a function ...
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### Recursive function activity

We had the following question on an activity for our students: Let $f_0(x)=x+|x-100|-|x+100|$, and for $n\geq 1$, let $f_n(x)=|f_{n-1}(x)|-1$. For how many values of $x$ is $f_{100}(x)=0$? When I ...
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### How does RootLocusPlot handle TransferFunctionModel

I'd like to analyze the poles (denominator-roots) of a TransferFunctionModel, that was generated from a ...
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### Through does not work with Subtract

Through[(Max - Min)[#]] & @ {1, 2, 3, 4, 5} gives 5 + (-Min)[{1, 2, 3, 4, 5}] Of course I can work around by ...
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### Having a function check a column and perform a task every time an entry satisfies a condition

So I have a matrix (technically a table) points = Table[{x, f[x]}, {x, Range[0, 2, .1]}]; Which gives something like this in matrixform \begin{array}{cc} ...
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### Plot a function with respect to two parameters that are not explicitly function parameters

$$function = |\delta|\frac{I_1(\kappa)}{I_0(\kappa)}$$ where $I_0(\kappa)$ and $I_1(\kappa)$ are the modified bessel functions of the first kind of order $0$ and $1$ I want to plot the function in ...
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### How to prevent a definition from overwriting my input

I developed the following manipulate code to be a limited knockoff of Polking's dfield. I export the code to Enterprise CDF so that one may type a first-order ODE into the input box and create a slope ...
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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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### Newton's Method Converges in Mathematica for non-convergent functions

In mathematica I set f[x_] := Sign[x] Sqrt[Abs[x]] and then I solved it in a root finding for Newton's method by doing ...
501 views

### Defining indefinitely many functions

Is it possible to define a class of indefinitely many functions f1, f2, f3, ... such that ...
55 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 does this code work to substract a set A from a set B?

In an answer to a question (as given here: code), the proposed function was to to subtract a set B from a Set A: ...
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### How do Reap and Sow work in this context

I have a list of points in 3D and I need to count how many times each point is repeated. For a similar problem with a list of characters many different solutions have been proposed in this post: ...
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### Issue plotting/re-creating 3d function

I am trying to re-create images created in Mathematica using the equations in the photos attached. I was able to somewhat plot the Equation 6 (Cartesian coordinates) Figure 4 using this code ...
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### How to Change Vertex List in a Grid Graph

I would like to actually change the vertices in a grid graph instead of simply changing the label. Ultimately, I want the vertices to be points on a plane. So if given a simple grid graph ...
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### Problem with Apply [duplicate]

I have am trying to obtain the average of the distance from the mean radius for each shot in a group of shots at a target. I am having problems with the very last line. The output of the last line ...
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### Approximate UnitStep for use in Enterprise CDF

The following Manipulate code displays the VectorPlot for all functions. (This code is a subset of a more extensive notebook which is based on the structure you see below. Consequently, I need to ...
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### Why does FromDigits transpose its argument (sometimes)?

a = {{1, 2}, {3, 4}, {5, 6}} ; FromDigits /@ Transpose@ a == FromDigits @ a (* True *) The only "strange" syntax I've found in the docs is But it doesn't ...
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### Why can't I use OmegaPrime to find the Limit of Prime[n]? [duplicate]

I've looked at these links already; What are the limits of the Prime-functions? What is so special about Prime? which gave an answer for earlier versions of Mathematica. Yet when I try to input ...
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### How to correctly scale the x axis?

I am not absolutely sure how to formulate my question but here is my first attempt: I have 25 rods with lengths in cm ...
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### what is the means of (0 -> 1) of series expansion [closed]

I use mathematica 8 to take a taylor expansion.In the Output, the expression (0->1) appears in the second term and all higher order term, and this expression is multiplied with other coefficient and ...
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### How would one return from a place of a pure function's body using Return?

From previous answers, replies and discussions it is known, while not formally documented (even in the most recent Wolfram Language Documentation Center), that Return can be used in a two-argument ...
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### Restrict domain of a function?

I have a function f[x,y,...,z] and I want to restrict its range to positive numbers only, f > 0. ...
183 views

### Convert FullForm to XML Structure and back

How might I create a function that converts between FullForm and a XML structuce? Ultimately I'm ideally looking to use CSS and JS to edited the XML structure. ...
145 views

### What kind of creature is h[c] for definition h[c_][x_] := (* function of x and c *)

To implement "Hero's Method" for approximating $\sqrt{c}$, one iterates the function (x + c/x)/2 for a given number c (e.g., ...
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### Optimization of recursive functions by using the //. operator [duplicate]

In some cases, recursion in Mathematica (without storing values) is not very efficient. For example, the recursive implementation of Fibonacci numbers (version which doesn't store the values) : ...
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### Why is an Identity function needed?

Today I came across the function Identity[x] in Mathematica (documentation). The example given in the documentation uses it in ...
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### How to create a vertical (smooth) Histogram on the y-axis of a function graph for an uncertain x?

This is my first time posting a question in StackExchange. I have encountered a certain problem and I can't seem too find a solution. Just a word of caution, I am kind of an amateur when it comes to ...
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### RootReduce-Part of Solve

I have given the following expression in $M$ and $z$: a = \frac{-4 M^2+M (-3 z-5)+\frac{1.1875 z}{\sqrt{\frac{0.015625 z}{M+1}-1.5625} \sqrt{\frac{0.765625 ...
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### Pattern and Orderless function

I'm a Mathematica beginner. I am exploring the use of patterns and (only for fun) am trying to implement a permutations function. My (dirty) code is: ...
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### 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 ...
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### Table generation with SetDelayed function [closed]

I would like to understand why the following two outputs differ: Let us define the following data set: ...
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### Working with CDF Deployment

I've been working with FreeCDFs in Mathematica 10 and it has been going fine as long as I do not pull from a database or access local files. I recently purchased the Mathematica 10.2 Enterprise ...