## 721 Reputation

15 years, 175 days

I have a degree in Mathematics and Physics from the Danish University Aarhus, comparable to a masters degree with thesis - majoring in Mathematics. In 1991-92 I was a visting scholar at UCLA, Los Angeles, following graduate courses in Applied Mathematics. Since 1992 I have been a teacher in a high school (gymnasium) in Denmark. Special interests: Applied mathematics, graphics and popularizing Mathematics.

## Explore command with an additional plot...

Maple

Dear Maple users

I have created a simple Explore command in order to display what happens with a Planck curve when the temperature T increases - using the slider. Especially I would like to show how the maximum of the curve lies in relation to the visible spectrum from 400-700 nm, that is from 4*10^-7 to 7*10^-7. My idea was to somehow have this wavelength interval representing the visible spectrum displayed behind the Planck curve as a vertical rectangle. If it was a fixed plot, I could do it using the display command, but is it possible to add an extra plot to an Explore command?

I have uploaded the temporary Maple file and an image to show my intention (I don't expect the coloring ...)

Planck_curve.mw

Maybe someone can help?

Kind regards,

Erik V.

## Solving system of equations including tr...

Maple

I stumpled upon an exercise involving calculating double points for the spacecurve for a vector function defined in the plane. It reduces to solving two equations with two variables. The command solve is usually the way to find solutions, but since the equation contain a trigonometric function, Maple gives the solutions parametrized by aritrary constants _Z and _B. It is however cumbersome to 'decipher' the possible solutions as I do in the attached Maple file.

I wonder if Maple have a way to deliver the solutions numerically in the interval from -4 to 4? If it had been a single equation this would have been possible, I know.

NB! I know I can use the symmetri in the current example, but I am interested in a general technique to solve these kind of equations.

Regards,

Erik

## Selecting numbers from random bins...

Maple

Dear people at Mapleprimes

My situation is the following: I have a number of bins (n bins), which all contain a specific number. I want to choose at random from these bins a number of times (N times), but in such a way that it is not equal likely that I choose from bin1, bin2 ...

Example: I have 5 bins: The 5 bins contains the numbers 50, 60, 70, 80, 90 respectively. The probabilities of choosing from these 5 bins should be 0.10, 0.30, 0.20, 0.25, 0.15 respectively. I make N = 100 selections. The output is expected to be a list with 100 numbers, for example: [ 50, 80, 80, 60, 60, 90, 50, ... , 70].

I could make it work myself by picking a random number from the uniform distribution from 0 to 1 and deciding if the a random number is between 0 and 0.10, between 0.10 and 0.40, between 0.40 and 0.60, etc. and then choosing the number in the corresponding bin ... I just wonder if Maple has an elegant way to to it?

Regards,

Erik

## Broken file associations in Maple 2020...

Maple 2020

Dear Maple users

I have had problems with Maple 2020. I am using Windows 10, by the way, and have several versions of Maple installed: 2019, 2018 and even 2017. Now however I am unable to open a Maple file from Windows Explorer either by double-clicking or by right-clicking and choosing "Open with" Maple 2020. Nothing happens when I try so! It works properly when I choose older versions of Maple. I have about the same problems on another computer, an Ultrabook. It is really a pain having to open Maple 2020 and then having to browse all the way down a file path ...

NB! I have tried reinstalling, but it didn't help!

I hope someone have an idea how to solve this issue. Can it be solved in the Windows Registry?

Regards,

Erik

## Plotting integers at specific locations ...

Maple

Dear Maple users

I just created a sunflower in Maple using the Golden angle. See attached file. I am using a scatterplot with solidcircles as symbols. But what I would like now is to plot integers instead of the solidcircles in order to investigate the order of these different solidcircles. To make it clear: I have 500 solidcircles. They have been plottet using two vectors containing the x and y coordinates of the individual solidcircles. The n'th solidcircle I want to replace with the integer n. How can I create that different plot?

NB! The plot might need to be larger or the integers smaller, but that is fine.

Regards

Erik V

sunflower.mw

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