1.18 Thursday, January 7, 2021

1.18.1 Top new questions this week
1.18.2 Greatest hits from previous weeks:
1.18.3 Can you answer these questions?

1.18.1 Top new questions this week

Why MMA refuses to simplify the following simple expression?
Simplifying code that displays a square rolling inside a circle
Trying to build a code to translate handwritten formulas using ML
How to define a function reminding of names of the independent variables?
Improve running speed for DeleteDuplicates
Why does Mathematica try to take the first element of the empty list when plotting?
Why do the frame ticks disapear when a plot is exported as PNG?

Why MMA refuses to simplify the following simple expression?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237547

I have the following simple expression Exp[(Log[1 + x]^2 - Log[x]^2)/Log[1 + 1/x]] - x^2

that can be shown to simplify to \(x\)

asked by user16320 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=16320 13 votes

answered by yarchik https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9469 5 votes

Simplifying code that displays a square rolling inside a circle

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237692

The vertex A,B of the square ABCD with side length \(\sqrt {2}\) is on the circle with radius \(\sqrt {2}\), vertex C,D is inside the circle, roll the square ABCD along the inside of the circle ...

asked by expression https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=7339 10 votes

answered by David G. Stork https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9735 0 votes

Trying to build a code to translate handwritten formulas using ML

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237533

I’m lazy writing equations in Latex so I want a code to translate handwritten equations. This question is related to an old experiment I’m reviewing during vacations, here. I’m trying to use ...

asked by Gluoncito https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8696 10 votes

How to define a function reminding of names of the independent variables?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237458

I am using a function with a lot of variables. There are 9 and sometimes more of them. In this case, it is difficult to memorize, which one stays on the, say, fourth position, and which one - on the ...

asked by Alexei Boulbitch https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=788 8 votes

answered by CA Trevillian https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=63039 2 votes

Improve running speed for DeleteDuplicates

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237681

How to make this faster? I want to remove elements that satisfy the condition below but it’s way too slow.

asked by anhnha https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=18805 8 votes

answered by WReach https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=142 10 votes

Why does Mathematica try to take the first element of the empty list when plotting?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237785

I’m using Mathematica 12.1.1.0. When I enter

asked by Jason Gross https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12258 7 votes

answered by Bob Hanlon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9362 3 votes

Why do the frame ticks disapear when a plot is exported as PNG?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237678

I am using M12.0.0.0 on Ubuntu and I have these two plots:

asked by valar morghulis https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=26937 6 votes

answered by Rolf Mertig https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=29 5 votes

1.18.2 Greatest hits from previous weeks:

What do the X and Y axis stand for in the Fourier transform domain?
How can I plot the direction field for a differential equation?
Is Mathematica worth it for me?
How to ask Mathematica to imitate Andy Warhol’s pop-art painting?
Figuring when the minute and hour hand coincide on a clock
Conversion of Sine to Cosine
Finding unit tangent, normal, and binormal vectors for a given r(t)

What do the X and Y axis stand for in the Fourier transform domain?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=85139

In Wolfram Mathematica the function Fourierhas the following declaration

Fourier[list]

And after a list is given to the ...

asked by user253956 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=29958 27 votes

answered by Hugh https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=12558 61 votes

How can I plot the direction field for a differential equation?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=8841

I’d like to plot the graph of the direction field for a differential equation, to get a feel for it. I’m a novice, right now, when it comes to plotting in Mathematica, so I’m hoping that someone can ...

asked by Matt Groff https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=1735 31 votes

answered by Peter Breitfeld https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=307 25 votes

Is Mathematica worth it for me?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=100072

I’m 13 years old and in 7th grade. I’m currently in Algebra 1, and I have fallen in love with both math and programming.

When I came upon Mathematica, it was awesome. My two favorite things fused ...

asked by Nico A https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=35769 81 votes

answered by Pillsy https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=531 55 votes

How to ask Mathematica to imitate Andy Warhol’s pop-art painting?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=59132

I tried to ask Mathematica to imitate Andy Warhol, let it convert a Marilyn Monroe’s portrait so that it looks like Warhol’s world famous pop-art painting. However, the result shown below is far from ...

asked by Putterboy https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=16069 52 votes

answered by Dr. belisarius https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=193 67 votes

Figuring when the minute and hour hand coincide on a clock

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=573

I would like to list all possible times in a 12-hour period, where the hour hand overlaps the minute hand completely. This is really a question about three distinct things - to be done in Mathematica ...

asked by Steve D https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=191 15 votes

answered by Verbeia https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=8 21 votes

Conversion of Sine to Cosine

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=67521

I’m solving equations with many Cosines and Sines. And I want to convert all the Sines to Cosines using trigonometric formulas such as cos(x)=sin(x+pi/2). How can I do this?

asked by YongCheol Kwon https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=23041 4 votes

answered by Sjoerd C. de Vries https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=57 2 votes

Finding unit tangent, normal, and binormal vectors for a given r(t)

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=18598

For my Calc III class, I need to find \(T(t), N(t)\), and \(B(t)\) for \(t=1, 2\), and \(-1\), given \(r(t)=\{t,t^2,t^3\}\).

I’ve got Mathematica, but I’ve never used it before and I’m not sure how to coerce ...

asked by a98 https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=5605 30 votes

answered by Artes https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=184 44 votes

1.18.3 Can you answer these questions?

Numerically obtaining inverse 2D Laplace transform
How to determine population from a list of arbitrary jurisdictions (cities, states, counties, et al.)?
Computing correspondences between two images

Numerically obtaining inverse 2D Laplace transform

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237480

I wonder if there is a function in Mathematica (or code) that can help obtaining inverse 2D Laplace transform of a function, f(s1,s2) which is the 2D Laplace transform of a function F(t1,t2) in (s1,s2)...

asked by Refaat Galal https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=76583 1 vote

How to determine population from a list of arbitrary jurisdictions (cities, states, counties, et al.)?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237541

I am an aspiring data scientist who’s working on a passion project, namely to assign danger-level scores to police departments in the United States. One specific metric I’m developing results from ...

asked by uselesslemma https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=72297 3 votes

answered by George Varnavides https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=41179 0 votes

Computing correspondences between two images

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=237484

A classic problem in computer vision is computing correspondences between keypoints in two similar images, despite modest variations in size, lightness, orientation, etc., of the images, as ...

asked by David G. Stork https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=9735 6 votes