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

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12
votes
2answers
273 views

Extracting the function from InterpolatingFunction object

I've used Interpolation[] to generate an InterpolatingFunction object from a list of integers. ...
4
votes
1answer
77 views

Possible bug / numerical issues with HypergeometricU — any suggestions for a fast workaround?

I've encountered some problematic behaviour with HypergeometricU. I have a probability distribution on the positive integers that takes the following form after ...
1
vote
0answers
60 views

Inconsistent linearity of inverse Fourier transform

Bug introduced in 8.0.4 or earlier and fixed in 9.0.1 or earlier I am trying to compute the inverse Fourier transform of this expression ...
34
votes
2answers
785 views

Why is the new PositionIndex horribly slow?

This issue has largely been mitigated in 10.0.1. New timings for the final test below are: ...
2
votes
1answer
67 views

Find constants in a function? [closed]

Let's say I have a function f[x] with n constants, e.g. f[x] = c1 * x + c2*x^2 + ... + cn *x^n I also have n conditions to find those constants, e.g ...
5
votes
0answers
171 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 ...
9
votes
1answer
213 views

Limit of sequence of functions behaving strange

I'm trying to determine the limit of the sequence of functions $$f_n(x)=\left(\frac{1}{\pi}\arctan(n x) + 1/2\right)^n. $$ I define ...
3
votes
0answers
65 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 ...
1
vote
1answer
39 views

Strange behaviour of Set and Part when given a sequence

Consider this example: lis1 = {a, b, c}; lis1[[2]] = Sequence[e, f]; lis1 (*{a, e, f, c}*) lis1[[2]] (*e*) lis1[[2]] = Sequence[g, h]; lis1 (*{a, g, h, c}*) It ...
6
votes
2answers
185 views

Is there a built-in function which detects singularities in a function?

Given a function f[x] and a region M in the complex x-plane, how can I find singularities of f in this region, i.e., issue a ...
13
votes
6answers
897 views

Will Version 9 functions all work in Version 10?

Having developed a substantial code base in Mathematica 9, leads me to ask these important questions prior to downloading and installing Mathematica 10. Will any Mathematica functions from the ...
3
votes
0answers
125 views

Generating function for Newton series?

The function GeneratingFunction gives generating function for Taylor series. Is there a similar function for Newton's series? $$f(x) = \sum_{k=0}^\infty \binom{x}k \Delta^k [f]\left (0\right)$$
5
votes
2answers
153 views

Strange Behavior when making Equal Listable in Pick

While trying to make this problem more efficient I tried different methods and dabbled with making Greater and Equal ...
1
vote
1answer
74 views

How can I export numerical data in a calculation-favorable format?

I am exporting some data into the txt file but since the values exported to this txt file expresses 10^6 to be *^6, I cannot use these numbers in calculations in other programs.. For instance, when I ...
1
vote
1answer
94 views

How do I link the txt file data sheet to mathematica and extract exact elements that I would like to use in solving for x? [closed]

I am trying to solve for a numerical solution for an equation which contains variables that evolves as index i incrreases. The actual equation that I am using to extract solution for x with an ongoing ...
3
votes
2answers
89 views

Wrapping Interval Notation for Take

I'm trying to implement the solution to a math problem in Mathematica, but my code can't handle a particular boundary case. I think that I could implement a function that would do what I want it to, ...
0
votes
0answers
31 views

System of Nonlinear equations with Gamma and Incomplete Gamma function

The next two nonlinear equations are cumulative ratios of a production system. The mathematical model includes two essential parameters (n, tau) that can be obtained by solving this system. I'm ...
0
votes
1answer
158 views

Finding real roots for an eigth-degree polynomial

The context for this problem is identical to my first question. Unfortunately my previous result for $L$ was inexact since it was a relatively simple approximation. This time I have managed to produce ...
7
votes
4answers
448 views

Solving $L=\frac{3}{2} \sqrt{4 \pi ^2 A^2+W^2}-\frac{\sqrt{5 W \sqrt{4 \pi ^2 A^2+W^2}+6 \pi ^2 A^2+3 W^2}}{\sqrt{2}}+\frac{3 W}{2}$ for $W$

When I solve the aforementioned equation for $W$ or $A$ on Mathematica I get a long and ugly equation in return, namely one of the solutions for $W$ is: (attempt to read at your own health) ...
10
votes
1answer
133 views

Why won't SparseArray let me store values with the head List?

When you attempt to define a SparseArray with elements that have the head List it complains: ...
3
votes
2answers
161 views

Get domain for a given function (including e.g. singularities)

I am new to Mathematica and this is probably a simple question, but I can't figure it out at the moment... f[x_]:=1/(x-3) Clearly the vertical asymptote is at ...
3
votes
2answers
227 views

What would be the inverse function for the following condition?

I tried the problem but i couldn't take above condition in question in terms of f(x)
4
votes
3answers
141 views

How to Nest a Function with three Arguments?

I have two functions with three arguments $f_x(a,b,t)$ and $f_y(a,b,t)$. And i need a nesting like this ...
6
votes
4answers
1k views

Use Mathematica to calculate the area enclosed between two curves

use mathematica Hence, calculate the exact area enclosed by these curves using Mathematica. $f(x)=x^3$ and $g(x)=x^5 - 2 x^3 - 3 x$ i have got the graph...now I'm stuck with finding the area
10
votes
4answers
494 views

Set of integers not divisible by smaller set of primes

Let $p_n$ be the sequence of prime numbers, and $s(x,n)=$ the set of integers less or equal than $x$ that are not divisible by $p_1,\dots,p_n.$ I can define it as follows: ...
8
votes
5answers
379 views

What is my problem with MeshFunction?

I want plot the max value in a sine plot. We can use the following code ...
10
votes
4answers
1k views

How do I plot Thomae's function in Mathematica?

I wanted to plot this function $$f(x) =\begin{cases} 1 & \text{if } x= 0 \\ \tfrac1{q} & \text{if } x = \tfrac{p}{q}\\ 0 & \text{if } x \in \mathbb{R}-\mathbb{Q} ...
8
votes
2answers
634 views

Can you apply the Cellular Automata function to a grid containing numbers?

Im attempting to simulate a simple evacuation model using cellular automata theory.My study aims to determine whether Cellular Automata can effectively represent how people would behave in a fire ...
4
votes
4answers
234 views

implement the ZOH in mathematica [closed]

well I'm trying to implement the ZOH in Mathematica, but I can't. Take a look, this is my script: ...
17
votes
5answers
6k views

How to find the domain and range of a function with Mathematica?

I'm studying calculus and in some exercises I am asked to find the domain and range of a function. Does Mathematica have already a built-in function for this? I can imagine some ways of doing so, ...
1
vote
1answer
97 views

Horizontally compress a picture with varying compression ratio [closed]

I have a function c[x] whose domain and range are both [0,1]. And I have a picture with width W, height ...
2
votes
3answers
264 views

How can I get the function of a plotted trajectory? [closed]

I solved two ODEs, which are a function of t, numerically. The first ODE is the vertical equation of motion and the second one is the horizontal equation of that ...
1
vote
2answers
54 views

How to use the output we see of expression when this expression is inside Dynamic

Consider this example: Manipulate[status = Dynamic[If[a < b, Yes, No]], {a, 2}, {b, 5}] The output of this calculation is ...
1
vote
1answer
82 views

Attaching functions to movable locators

I'm trying to create a manipulate plot showing the electric field due to a collection of point charges. At the moment I've created such a plot which allows the x and y positions of each charge to be ...
10
votes
2answers
225 views

Why isn't Lookup treated like other symbols?

With Mathematica 10, I wanted to overload Lookup using TagSetDelayed, but it doesn't work. For instance, if I define two objects ...
21
votes
2answers
455 views

Why is Query so much slower than Part?

Time for another of these(1),(2) as yet another new-in-10 function appears to have poor performance compared to older alternatives. This time: Query appears to be ...
1
vote
1answer
147 views

How to apply a tensor to a list of arguments

The problem I have is the following: Let C be a list of coordinates, say, C = {x1, x2, ..., xn} and ...
2
votes
1answer
132 views

RegionPlot3D run forever when plotting 3D ParametricRegion

when working with 2D, RegionPlot works fine with ParametricRegion as can be seen in this example: ...
3
votes
2answers
462 views

How to plot several functions without jumping? (multiple eigenvalues of a system as functions of 2 parameters)

I've been working on this research problem for months with some success by no global/proper solution to the problem. So I have square, Hermitian matrices of various sizes ($8,20,38$ dimensions) with ...
1
vote
2answers
90 views

How to define logical expressions for platonic solids?

A more general question would be: How to find logical expressions for 3D-objects described by closed polygon sets? Finally a simple question is more prolific, therefore: How to define logical ...
3
votes
5answers
283 views

How to add periodicity to condition?

Is it possible to set the following function f[a], where a can be any real number? $$ f(\alpha) = \begin{cases} 1 ...
0
votes
2answers
247 views

$RecursionLimit::reclim: Recursion problem

Please, find bellow my original question. Here is all my code: ...
2
votes
1answer
108 views

Define PolyLog so that positive reals evaluate on upper edge of branch cut

Generalizing the previous question: Define Log so that negative reals evaluate on lower edge of branch For real positive values $x>1$, Mathematica's polylogarithm function ...
2
votes
1answer
192 views

Finding average error of the data

Considering I have some data, and I want to fit the data to a linear fit and find the average error from the linear fit, how can I do that using Mathematica? I have ...
0
votes
0answers
27 views

How to prevent function from substituting the part of the parameter name if it has a subscript? [duplicate]

I have the following problem, when defining and using a function, that's supposed to have an outside parameter xmin: A[x_] := Exp[-x/Subscript[x, min]] A[5] ...
-2
votes
1answer
62 views

Compile Determinant [closed]

I would like to determine the determinant of a 4x4 matrix with the entries a[i,j] being functions of $i$ and $j$. I used Compile with code: ...
5
votes
1answer
188 views

How can I make a “self-referential” replacement operation self-contained?

Fairly often I find use for replacement rules that call themselves on the right-hand side of the rule, e.g.: ...
1
vote
0answers
89 views

How do I choose only one branch of ArcTan?

I have a problem concerning ArcTan drawing a graph using ListPlot. I import a table of data: ...
2
votes
0answers
37 views

Evaluating standard functions of general quaternions symbolically

Mathematica can easily compute exponentials and logarithms of concrete quaternions: ...
2
votes
1answer
99 views

How to explain the behavior of Rule inside these functions [duplicate]

I'm trying to define a function that takes an expression and spits out a pure function involving a replacement rule of that function's variable. An example would be a function ...