Questions tagged [functions]
Questions about the use of built-in Mathematica functions, including pure functions.
235
questions with no upvoted or accepted answers
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79 views
Plotting Asymptotic Series
I apologise for being always here asking for the same questions, but I need to learn.
I have to plot this series
$$\frac{\pi}{2} - \frac{\cos x}{x}\left(\sum_{k = 0}^{+\infty} (-1)^k \frac{(2k)!}{x^...
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0answers
47 views
Extracting elements with a certain criteria from a pre existing list
Here I take just a random list of triples of size 10
...
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0answers
104 views
ListDensityPlot erroneously showing flat regions (NOT plot range issue)
I have a dataset (listed below). I'm trying to plot the dataset using ListDensity plot;
...
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0answers
308 views
Defining a piecewise function where the conditions are points
I am trying to define the following function in Mathematica:
$$pw=\begin{cases}
x y \cos \left(\frac{1}{x^2+y^2}\right) & (x,y)\neq(0,0) \\
0 & (x,y)=(0,0)
\end{cases}$$
I want to use this ...
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0answers
224 views
An array of functions
I need to define an array which every entry is a function. To be more specific, I want to solve the equation:
$$\frac{d \rho}{dt} = -i[H, \rho] + L[\rho]$$
in which $\rho$ is a matrix. This is a ...
1
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0answers
70 views
The wire frame from a Plot3D gives a jumbled mess for a wire frame
Some time ago I found a post that turned the triangles of a mesh into polygons. I have spent 2 hours looking for that post and can not find it.
The problem: Plotting
...
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0answers
231 views
How to get user input using FormPage
I am designing a user interface for a word-ladder game using CloudDeploy, CloudExpression and FormPage and I am having trouble with receiving the user input from the form. What I basically need is a ...
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0answers
55 views
Is there any point to using a variable as a function parameter?
Normally one only sees patterns as function parameters:
fun1[x_]:=x^2
Is there any point to using a variable in a function definition:
...
1
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0answers
38 views
Function with many lines that takes image as parameter not returning same result as if I run the same lines of code
Running the exact same lines of code in a function produces just a return of the original image without any points identified, whereas when I run the exact body of the function line by line it works ...
1
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0answers
80 views
Finding correct combination of functions
I am trying to write code where I have an array $S$ or numbers in any order [5,4,2,1,....]
Then I have a specific set of functions that I can write. ...
1
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0answers
191 views
Help with calculating a complicated integral
Edit: The question is solved : )) Thank you for your attention !
I am sorry for mass questions, but the question bothers me a lot. So I would like to ask this question here.
This problem arises when ...
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0answers
51 views
When evaluating this integral Mathematica returns two different answers
When evaluating this integral in Mathematica 10.3 Student Edition:
...
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0answers
46 views
Defining an object which is function in some variables and tensor in some other indices
I am trying to define an object which function in some variable and tensor in other indices.
My attempt at it was:
...
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0answers
102 views
DiracDelta of a function
If I have, for instance,
FunctionExpand[DiracDelta[x^2+x-3]]
it evaluates to
...
1
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0answers
85 views
Which method to use for finding maximum without actually computing optimization function explicitly?
I am new to Mathematica and I am currently working on an optimization problem. The optimization function that I have easy to calculate for some assignment of variable but it is very difficult to ...
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0answers
239 views
How to simplify an expression with a radical sign nesting in a radical sign
Is there a function can simplify an expression with a radical sign nesting in a radical sign in Mathematica? I use V9.
RatDenmon is a function that can ...
1
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0answers
68 views
Input `Reduce[Mod[a + x, l] == 0, x]' and output `x == -a + kl`?
Reduce[a + x == k l && k > 0, x]
(* k > 0 && x == -a + k l *)
I think a + x == k l and ...
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0answers
99 views
What are the differences between these functions when used for NMaximize?
In short, the question is how to construct the function you want to optimize?
...
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0answers
95 views
Improving RationalInterpolation Result
The following code produces a {4,4} rational interpolation approximation accurate to 10^-6 or better over the range ...
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0answers
467 views
Crosscorrelation for nonperiodic signals
I want to detect patterns (of an absorption spectrum which is nonperiodic) with Mathematica automaticly. I have found CorrelationFuncion but as far as I understand, ...
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0answers
221 views
RowReduce doesn't work for this matrix?
I have this matrix
A={{0,1,1,w},{1,0,1,x},{-1,0,1,y},{0,1,1,z}}
where w, x, y, z are arbitrary constants. This matrix should be row reduced to the form
...
1
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0answers
61 views
Is it possible to calculate with declarations only?
simple Example:
maximize $u(x), x$
solution would show constraints:
$\frac{\partial u(x)}{\partial x} = 0$
$\frac{\partial^2 u(x)}{\partial x} < 0$
etc...
or do I always have to explicitly ...
1
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0answers
417 views
Expression for evaluating multiple functions?
I am constructing 3D data points for a plot and corresponding to specific conditions "manually". I define the values of five parameters [these I always have to define myself]. From those, I evaluate ...
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82 views
Distinction between 2 NETTypeInfo answers
In a NETLink application I checked all the types offered by LoadedNETTypes[] according to the following:
...
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0answers
95 views
Decapitating “explicit” and “implicit” heads
This is a follow up to this question.
So far, I named "explicit" heads to those that appear explicitly in the expression. For example, f[x] has an explicit head. I ...
1
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0answers
202 views
parameter NDSolve
the question I need to solve is:
t x'[t] == -x[t] + y[t],
t y'[t] == -5 t^2/x[t]^2 + x[t] - y[t],
x[1] == 4, x[b] == 1
in order to solve the coupled ...
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0answers
165 views
CDF with numerous independent manipulate objects
I have been working on my senior project that involves the creation of a CDF with multiple Manipulateexpressions. I need to protect my code so I have been trying to ...
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0answers
164 views
Does Graphics`Mesh`SimplePolygonQ[] work for you?
Graphics`Mesh`SimplePolygonQ is an undocumented function. I'm using Mathematica 7, and when I try:
...
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0answers
110 views
Solving for vector elements in a function to which the vectors are not passed explicitly
I want to define a function which takes in two integers (indicating the lengths of 2 vectors), and solves a simple set of expressions at a set of points to find all the values in both the vectors.
so ...
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0answers
50 views
Simplifying polynomial fractions with same `DiracDelta` function in both denominator and numerator
I am trying to simplify an expression with multiple Diracdelta functions in both numerator and denominator. For example,
...
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0answers
35 views
Defining a function and order of operations
I feel I have a profound misunderstanding of how Mathematica works. Here's an example that confuses me: Say that for a matrix $A$ I want to extract the first $\mathrm{Tr}(A)$ normalized eigenvectors (...
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0answers
43 views
Delayed Rule right-hand-side mis-evaluation
Outline
I am trying to create a rule that will give me a minus sign if the number of times A is applied on X is odd where A is some οperator and X a random quantity.
Some of the configurations of ...
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0answers
27 views
Creating a special product function
I am having trouble working with lists inside functions with Mathematica. Basically, I have a list of numbers and a special way to multiply them. I want to have a function that is able to create a ...
0
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0answers
37 views
Get R^2 value between interpolating functions and a list of points
I am looking to compare the degree of accuracy of a theoretical model by comparing my theoretical curve to my experimental data points.
My theoretical curve is an interpolating function generated ...
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0answers
45 views
Define a function including two solve solutions
I'm trying to combine the solutions coming from two NSolves and define a new function that I've to integrate.
Basically I've defined two ...
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0answers
19 views
InverseFunction cannot evaluate negative arguments
I have difficulty figuring out where my code fails. I want to obtain $\textbf{ry}$ which is the inverse function of rho (see below). When I input positive values for its argument, there's no problem. ...
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0answers
28 views
Easiest way to simultaneously keep track of two values in a list
I have a bunch of functions a,b,c,... that all take in a list of images and return a list consisting of a list of transformed images, and a number (let's call it ...
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0answers
76 views
NSolve not solving my transcendental equation
Would be grateful for your help in tackling this complex polynomial where I am trying to solve for x. When I run the code below, I get the message:
value x of ...
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0answers
24 views
Factor[p(x), a, b] not working in Galois theory package
I have downloaded Galois theory package from http://library.wolfram.com/infocenter/Articles/2872/ and I currently have Mathematica v 12.0.
When I loaded the module (I needed to delete the blue stuff ...
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0answers
35 views
Define the partial derivatives of a multivariable function
I have some vector $K = [K_1, K_2,...K_n]$ which is a function of variables $(x,y)$ i.e. $K = K(x,y)$
I want to symbolically calculate the partial derivatives e.g. $\partial_x K$, $\partial_x \...
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0answers
49 views
How to turn an algorithm into a function
I have written a script to help me find the several local minima of a dataset. It takes two arguments: the dataset list and an x-coordinate value that tells the script from where to start looking for ...
0
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1answer
98 views
Automating a large operation by making a function
I would like to automate the following operation. To be transparent I shall put my code into separate chunks and explain the process. Suppose I have the following:
...
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0answers
34 views
How to define a function in an implicit form
Know the 2-variables function $F(x,y)$. How can I define the function $x\to f(x)$ s.t. $F(x,f(x))=0$?
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2answers
80 views
Array of polynomials
So I have a big list of 75 polynomials which I need to apply a sequence of operations to.
My original program (an extract of which is below) worked fine:
...
0
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0answers
47 views
Function works outside For loop but not inside, and loop fails spectacularly
I'm building two lists, each to carry a different representation of the same set of objects. One list, list2, is constructed first; then the second list, ...
0
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0answers
65 views
How to list all the possible functions of given structure?
I can run this command :
Tuples[{ Tuples[{x, y, z}, 2], {a, b, c}}]
to list all combinations that looks like:
...
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0answers
39 views
Function iteration
I wrote a function in Mathematica that applies certain construction steps on the "incidence matrix" of a graph in order to obtain a new graph with certain properties. These construction steps can be ...
0
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0answers
87 views
Problem with fitting
So I have a very simple question related to a simple topic, but also directly related to a fitting problem.
I see that my question is related to this question but I don't manage to make the bridge ...
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0answers
40 views
Obtaining the equation type of an interpolated function
I used InterpolatingFunction on a set of points.
How can I know the type of that equation ? (polynomial, sinusoidal, logarithmic,etc...). I am looking for a general case answer.
Here is an example ...
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2answers
59 views
Problems with creating a matrix with functions
I have a function which gives me all the coordinates of a certain bloc in a lattice (with the help of another function for rows and columns):
...
