C_R

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5 years, 314 days

MaplePrimes Activity


These are replies submitted by C_R

@Christian Wolinski 

Intersting detail. map  (a built-in function) must have undergone some changes.

Maple 2024

map(map@`^`, eqs, 2);
                  [ 2    2   2    2   2    2]
                  [a  = b , c  = d , e  = f ]

Maple 2020

map(map@`^`, eqs, 2);
Error, (in evalapply) invalid input: map expects 2 or more arguments, but received 1

Your variant works in both versions.

@Kitonum 

Thanks, for the work around. The use of ~ is only required for multiplication. Also here equations cannot not be treated the same way with arithmetic operators.

@acer @nm

On a faster machine (about 3 times on these specific worksheets) the effect is much less pronounced.

@acer 

It is only since I expanded animation frame count for continuous rendering in a recent worksheet.

I tested Maple 2023 with it. After execution (all animation were rendered expected) I could not edit anything at all. So Maple 2024 performs better but still not satisfactorily.

@nm 

Auto save is on 7 min.  I do not think that it is related to it because I can see when autosave is working and has finished.

@mmcdara 

Before running the 6 hours test I tried the other idea somehow: f1-f2 until f5-f1. The equations to be Fsolved became bulkier than the original ones.

Not a single root with

T := Isolate([seq(F[i], i = 1 .. 5)], [x1, x2, x3, x4, x5],maxroots=1,mthd=RC): j := nops(T);

I canceled after 6 hours.

@acer 

The ghost image was caused by an error of mine: p1 should have been removed from the display statement.

For the rest I can work around.

The loss of the red color of the cube is still an open point but not a road block at the moment.

Thank you
 

@acer 

Ok, it seems that the effect of jagged shading can be dampend by finding forgiving plot options. However "closed" surfaces (I mean generated over 2 Pi) show the artefact even with no color (context pannel No color, Light 4 and Transparency 0.25). If this is not a graphics card artefact, it is perhaps a numerical artefact (hardware floats?). Or a Maple algorithm could be improved in the respect. Neighboring facets of a continuous surface should not show such discontinuities.

I think I can work around this this time.

The more severe mudding: Rotating the plot reveals structures that should simply not be there. It looks like as if plots:-sphereplot (here sphere moved to 0.9)  has generated structures out of the plot range and hiden them by making them fully transparent. Plot with the option transparency let them appear again. Could this be?

PS.: I forgot to mention. Also in  https://www.mapleprimes.com/view.aspx?sf=305936_Answer/multiple_animations_02.mw a cube lost completely its red color.

@Hullzie16 

Interesting way to remove brackets from expressions. I will see if I can make use of it next time I want Maple to generate code from Maple expressions.

@acer 

Its clear now what's happening.

Thank you for all the details!

Maybe the data structure to construct a matrix plays a role. Which one do you use?

@acer 

For some reason I thought the frames for the second animation call were set to 150. I was probably a bit overworked and annoyed by the upload problem.

I constructed the example upon your reply for discussion. Here is a corrected version (which is the second way I described above)

multiple_animations_02.mw

The example and the system of odes is simple but already shows what I expected: plotting a space curve with odeplot is much faster that using plottools. However, I am a bit surprised how fast it goes and I would for this example not write a procedure. The dependence of the cpu time on the number of frames and the integration time is instersting to observe. Its not excluded that the the third way will take more computation time than the second way if space curves are involved.

For complex and/or numerically demanding cases with long integration times one could think of reformulating at each time step IVP with dsol(timestamp).This does not work straight away with

(first time I am seeing dsolve solutions this way).

My question has somehow been answered: Try the second way and estimate computation effort and then decide to optimize with the thrid way. For that it would be good to be able to reformulate the IVP. This is the remaining question I have at the moment.

@acer

I wanted to attach an example with 3 plots to be displayed together (without letting the cube spinning for a moment). But I am getting this here
Ein Bild, das Text, Screenshot, Schrift enthält.

Automatisch generierte Beschreibung

I had to delete the last plot structure and it worked.

And yes, I thought odeplot is in this sense optimized that the integration is done once or at certain points in time odeplot stores intermediate results and uses them as new initial conditions.

multiple_animations.mw

Uploading the code with the green arrow makes investigations easier.

Without knowing the pde and the initial/boundary conditions its difficult to tell. However, the error message gives already a hint that the timestep for sol2 is too large.

If you want to keep this time step you could try to play with with numeric methods and options. See ?pdsolve,numeric

 

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