All Questions
93,929
questions
1
vote
1
answer
74
views
Can Mathematica check if I correctly applied an algebraic transformation?
Mathematica has tons of functions to perform algebraic manipulations. But is there a way to use it to check if I didn't make mistakes in my own algebraic manipulations.
As a real world example:
[...
- 1,509
4
votes
1
answer
113
views
How to find the operand of a sinusoid?
For a function $\sin[2x]$, the operand is $2x$. If we want know the value of the operand by hand, the function is simply $\arcsin(\sin[2x])=2x$. How to do this with Mathematica?
Here's what I tried:
...
- 1,336
0
votes
1
answer
239
views
finding the correct interpolation accuracy [closed]
Ciao,
I need to interpolate this data:
...
2
votes
0
answers
161
views
How to recover plaintext from .MX files?
I need a function to deserialize the contents of an MX source file for reading. We can’t simply use Get because I don’t want to load or run the code, but rather to ...
- 3,583
3
votes
1
answer
173
views
PubChem Service doesn't support isomeric SMILES specifications?
Update 04 Sept 2020: The problem described below occurs in Mathematica 12.0. It has been fixed in Mathematica 12.1, so that ServiceExecute returns the correct ...
- 3,356
0
votes
1
answer
73
views
Creating a custom curved axis around a pie chart
In a recent post, we have seen (thanks to @kglr) how to create a custom pie chart
...
- 8,760
1
vote
0
answers
86
views
Image segmentation on the edge (no pun entended)
I want to detect nuclei from unevenly stained images, which works quite well with LocalAdaptiveBinarize. Unfortunately, in many of these images the imaged area does ...
- 1,354
5
votes
2
answers
142
views
ListPlot3D with individual colours for each point that blend
If I have a list of points {x,y,z} and for each point an rgb colour, e.g.:
points={{0,0,0,1,0,0}, {1,0,0,0,1,0}, {1,1,1,0,0,1}}
how can I plot the surface covering ...
- 195
3
votes
1
answer
209
views
any way to stop all the following evaluations?
I often slect the whole notebook to evaluate. Sometimes some functions may return wrong parameters, which may happen, for example, I may have forgotten to specify values to some variables in the ...
- 725
1
vote
0
answers
136
views
How to map 2D coordinates to a unique colour (i.e. 2D colormap)?
Colourmaps in Mathematica usually map a single value with a colour.
Are there 2-dimensional colourmaps available where one can map 2d coordinates to a unique colour? (i.e. in a way that coordinates ...
- 195
1
vote
1
answer
2k
views
0
votes
0
answers
125
views
solve a differential equation numerically
I have to solve numerically an equation of the form
...
- 101
1
vote
0
answers
230
views
How to solve ode with convolution?
my question is as this and i want to get the solution of this ode x(t)
$
({M_{33}}{\rm{ + }}{{\rm{m}}_{33}})x''(t) + \int\limits_{ - \infty }^t {x'(tau){K_{33}}(t -...
- 615
1
vote
1
answer
80
views
How to test if $ⅈ$ is in an expression?
From this answer https://mathematica.stackexchange.com/a/9773/68791 and according to the documentation:
FreeQ[list,form] test whether form occurs nowhere in ...
- 1,509
1
vote
1
answer
44
views
Annotating variables in replacement rules
How do you decorate or annotate a variable in a replacement rule?
For example
{(e[(-X + Y)^2 || f])} //. {e[(-a_ + b_)^2 || f] -> (-a + b)^2}
Would ideally ...
- 624
6
votes
2
answers
2k
views
How to draw a phasor animation with Mathematica?
There is a nice animation on the Phasor Wikipedia page:
I wonder if (and how) one could draw such animation with Mathematica?
I'm not necessary interested in the code required to draw the exact same ...
- 1,509
5
votes
2
answers
259
views
Importing graphs from geng incrementally
Is it possible to import graphs generated by geng (a tool from the nauty suite) one by one, rather than all at once. If one could also specify not only the order ...
- 647
3
votes
1
answer
91
views
ReplaceRepeated with special characters: Alternatives
Following the advice here, I tried to replace part of an expression guided by the FullForm details:
...
- 624
1
vote
0
answers
26
views
Weird result comparing the errorformula with the actual error using the trapezoid method [closed]
The graph I got using the code in the link is VERY peculiar to say the least. I have no idea what's causing it.
https://community.wolfram.com/groups/-/m/t/1840718?p_p_auth=PKMDl2TX
- 11
2
votes
2
answers
125
views
Help me to set up equation for FindRoot to solve
When I run the code I get this error message:
FindRoot::nlnum: The function value {Eq1 - 0.08*Eq2} is not a list of numbers with dimensions {1} at {d} = {0.001}.
How can I correct the error and ...
- 23
5
votes
1
answer
203
views
How to author a workflow?
I find the workflow refpages in the doc center very helpful, and I'd like to make some of my own:
Workflows seem to be notebooks of "Text" and ...
- 31.5k
1
vote
1
answer
3k
views
How do I use ListPlot with error bars properly [closed]
I'm trying to make a ListPlot with error bars: In this example I want one data point at x = 3, y = 1 and symmetric error bars of magnitude 0.5.
This is the code I'm using
...
- 167
0
votes
1
answer
183
views
Programatically generating variables and sum
Given a set of variables, say s1through sn, and a way to generate an expression expr ...
- 2,355
6
votes
1
answer
102
views
Wrong domain of 1/x
I am experimenting with Reduce. I found a weird behavior. Consider this example:
Reduce[Element[1/(x + 1), Reals], x, Reals]
This should produce the domain of ...
- 61
1
vote
1
answer
302
views
2
votes
0
answers
228
views
Phase portrait of n-dimensional state-space system
It is usually not difficult to study the state space for n = 2,3 variable states.
What if these variables are more than 3, for example 4,5 or 6?
There is a rule according to which the dynamic features ...
- 2,394
-1
votes
2
answers
98
views
solve a matrix differential equation numerically [closed]
I want to solve numerically a differential equation like
iy'[t]=y[t]/20
where y is a 2*2 matrix and i is iota.
Please suggest me a way to proceed.
- 101
2
votes
2
answers
128
views
Statistics in an array [closed]
I have the following data:
data = {{0.73, 0.75}, {0.70, 0.67}, {0.76}, {0.84}};
where the elements of data (data[[i]]) vary in length.
I need to make statistics ...
- 1,301
5
votes
1
answer
102
views
What is the proper way of setting ` CellContext -> CellGroup` in the Wolfram Cloud Notebook?
I want a different evaluation context for different sections of my Notebook.Mike Honeychurch suggested to me than changing the CellContext to ...
- 1,509
1
vote
2
answers
162
views
contourlabels diagonally
I have this contour plot.
I want to place contours diagonally in the center of the plot. or put custom labels where I want. how can I do it?
I use this command for contourlabels. but it is not ...
- 147
5
votes
1
answer
364
views
Solving partial recurrence equation with several recurrence indices
I'm trying to solve a recurrence relation for a function of three variables. It works with 2 variables but not with 3.
A simple example is:
...
- 51
1
vote
0
answers
96
views
The order of partial derivatives on a symbolic function
I was wondering if it is possible to get the partial derivative of a symbolic function while maintaining the same order of derivation.
Here is what I get when I plug the following command:
...
- 11
3
votes
1
answer
127
views
Create a custom diagram
Suppose we have the following list with a row of integer numbers
data = {0, 0, -1, 1, 1, 2, 9, -2, 2, 1, 1, 1, 0, 0, 9, 9, -1, 0, 9, 2}
Each integer corresponds ...
- 8,760
3
votes
1
answer
149
views
How to use Tube (and regionplot) for this parametric plot?
ParametricPlot3D[{(1 + Cos[Theta]) Cos[Phi], (1 + Cos[Theta]) Sin[
Phi], Sin[Theta]}, {Theta, 0, 2 Pi}, {Phi, 0, 2 Pi}]
How do I use ...
- 1,550
1
vote
1
answer
152
views
How to use Collect in Mathematica [closed]
For an input $n$, I have $n^2$ variables uu[1,1],...uu[1,n],...,[n,1],...,uu[n,n].
I have an equation that is linear in these (e.g. ...
- 245
0
votes
2
answers
144
views
Parallelize[] dos not parallelize sum of integrals [closed]
I am not sure why this simple command cannot be executed in parallel.
Parallelize[ Integrate[ Sin[x], x]
+ Integrate[ Tan[x], x] ]
Error message:
Parallelize:...
- 1,678
2
votes
1
answer
144
views
Fractional Euler-Lagrange equation [closed]
Using Mathematica, I need to perform the derivation of the fractional Euler-Lagrange equation as derived in this article.
Regarding this, I searched many links, but I was not able to master the ...
- 353
2
votes
0
answers
169
views
Mathematica 8 won't launch on Fedora [closed]
I installed Mathematica on Fedora 31. Installation went fine. No errors. When I start Mathematica from temrinal, I see the banner, GUI opens up, and I see an error in the terminal :
There was an ...
3
votes
0
answers
92
views
Installing R failed
To install R, I evaluated the following code
Needs["RLink`"]
InstallR["RHomeLocation" -> "C:\\Program Files\\R\\R-3.6.1"]
and I ...
- 31
0
votes
2
answers
42
views
Why MaxValue and Nmaximize doesnt aproximately match?
I want to find the maximum value of the following function of three variables $(x>0,y>0,z>0)$:
...
2
votes
1
answer
71
views
8
votes
2
answers
609
views
How to mix text and formulas in a single cell in the Wolfram Cloud Notebook?
How to mix text and formulas in a single cell in the Wolfram Cloud Notebook?
The shortcuts Ctrl+( and Ctrl+( don't work (they probably are intercepted by the browser)
- 1,509
1
vote
2
answers
145
views
How to keep symbol bindings local to a Notebook section?
I'm using the Notebook on Wolfram-Cloud as a ... well ... notebook to keep notes about the topic I'm studying and to answer exercises. I usually keep one notebook file per chapter, with course notes ...
- 1,509
0
votes
1
answer
50
views
The graph doesn't generate
I try graph the partial derivative of this function but it keeps giving me the "invalid variable".
What I am trying to follow is:
1. Take the derivative of the function respect to T only (To and Eo ...
3
votes
1
answer
613
views
Formatting error in Mathematica 12
Recently, my copy of Mathematica v.12 started reporting the error
An improperly formatted directive with head Times was encountered.
on startup.
This error also shows up in the Messages window ...
- 71
1
vote
1
answer
231
views
How to "undo" an outer product
I have a matrix which is formed from the outer product of two complex vectors. There is some noise as well. How can I get the best estimate of the complex vector?
Here is a case without noise for a ...
- 16.5k
3
votes
2
answers
1k
views
0
votes
0
answers
119
views
Speed up and Smooth Plot3D of NDSolve Evaluated Results
may I ask is there any space for my code to be improved in terms of the speed and resolution of the plotted results. Currently, it takes more than one hour to plot the 3D graph and as shown in the ...
- 25
2
votes
1
answer
71
views
Question on combining 2 datasets with common key
Hi I'm trying to combine 2 datasets with a common key which I'm not able to resolve with JoinAcross. 1st dataset is
...
3
votes
1
answer
615
views
How to change the font in LineLegend?
Is it possible to change the font in LineLegend? In fact, I need a mathematical font (like Times) in this part.
- 693