## PDF export of color-bar using densityplot...

I was trying to use the idea explained in this post (), using densityplot to create a barplot. But there are several difficultes specially using new Maple that has problem with exporting plots in pdf format the same as displayed inside Maple.

The example code:

zmin := 0;
zmax := 1;
verthuebar := plots:-densityplot(z, dummy = 0 .. 1, z = zmin .. zmax, grid = [2, 10], style = patchnogrid, size = [90, 260], colorscheme = [ColorTools[Color]([0, 0, 1]), ColorTools[Color]([1, 0, 0])], style = surface, axes = frame, labels = [, ], axis[1] = [tickmarks = []], axis[2] = [tickmarks = [aList[1] = "0   ", 0.5 = typeset(alpha* ), 1 = "1    "]]);

Problems:

1- When I export the bar-plot as .eps, it shows white lines as a grid, while I don't want it and it is not the same way it is displayed at Maple!

test-1.pdf

I tried adding gridlines=false and other similar things, but had no effect. I changed 10 to 3 in grid = [2, 10], but it increases the distance of 0 and 1 from the borderies and therefore wrong numbers will be read from the color bar. Exporting the picture as .pdf doesn't have that gridlines problem, but destroys the proportions of the image, so I want to stick on the .eps one, but without those white lines.

2- How can I have 0 and 1 exactly on the start and end of the color bar and with no distance from the edges? I can use view=[0..1,0..1] at the end of the above code, but depending on the number in the grid=[2,n] that I choose, the colors may not start and end exactly at the specified colors.

## CUDA support in Maple?...

I just got a "new" graphics card, NVIDIA GT630, and was wondering whether the CUDA capabilities are accessible. But no luck:

CUDA:-Enable();

Error, (in CUDA:-Enable) CUDA not supported on the current system (see CUDA,supported_hardware for more information)

The CUDA help page with the example, when run, just shows a host of error messages.

I have OS X 10.11.6, the above mentioned GT630 card with claimed 384 CUDA cores and 2 GB of VRAM; NVIDIA WebDriver 346.03.15f16 for the card (i.e. latest for this OS) and NVIDIA CUDA driver 8.0.90 (again, latest for this OS as far as I can tell). My Maple is 2015.2. All this running on a MacPro 4,1.

I am not having great illusions about the performance I should get (this is not a state-of-the-art card today), but it seems to me this combination should be working with Maple 2015 and not throw an error, shouldn't it? Checking the system extensions: CUDA.kext is loaded and its dependencies are satisfied, so I don't see any problem there.

Am I missing something?

M.D.

## Slow interface -- large latency between keystroke ...

I'm having an issue with Maple 2020.2 classic interface being *very* slow on a new MacBook pro with Big Sur. It takes about 1 second between each keystroke and it appearing on the screen.

Is this a known bug?

I want to read file dates (for data files) from inside Maple.  Specifically, I want to automate the comparison of access dates.

I thought I'd done this in the past, but my attempt to recreate it has led me to think that I am remembering incorrectly.

Is there a way of doing this?

I don't deeply care about portability (I'm working on Windows 10 and that would be good enough), but since I'm asking the question please comment on the easiest way to make this portable.

I am aware that by default Windows 10 doesn't update the access date.  On the machines I care about, I have changed the configuration so Windows is updating the access date (often enough for my purposes).  I have PowerShell scripts that work correctly.

## Grid toolbox and distributed computing....

I have several questions about Grid Toolbox. I am getting into distributed computing for a very large problem I have been working on for a long time; I am working on the simple examples that come with the Grid package, and I am not having much success. I am fairly experienced in Maple but I need help with this. My e-mail is harrisjtster@gmail.com.

## How do I solve the attached problem in maple?...

Hi,

I would be really grateful if someone can help me in solving the below attached problem in maple.

## How do i plot a wedge cut 3D graph in maple?...

Plot the wedge cut from the cylinder x²+y²=1 by the planes z=-y and z=0.

## How do I solve numerically a set of non-linear int...

Hey everyone,

f_1 and f_2  are satisfying the set of non-linear integral equations I have attached to this message.
I know that I need to solve them numerically by iterations. Probably, the first guest of the function f_1 and f_2  is the driving term. a is just a parameter which can be fixed (I guess smaller than \pi/4). * is the convolution product and k is the momentum space parameter. I learnt that in order to solve them I should solve them in the Fourier space. I know also that I need to discretize these function in the “real ” space between {-L,+L} before applying the FFT or one of its relatives. Thank you for any suggestions or leads.

## Simple interface question about default zoom level...

Hi,

I noticed that, in Maple 2020.2, the caracters seem smaller. As if the zoom had somewhat been reduced (a bit).

However, in the preferences, the default zoom level I would like is between 100 and 125% (something like 110%) (since the default zoom level is adjusted by steps of +/- 25%). I wondered if there was a way to set the default zoom level to an arbitrary value. In fact I thought it would be great to have a field instead of a list of choices, so we can choose a custom value.

Thank you

## How to eval integration under loop...

Here is my try to integrate the expression L with trapozoid or simpson

numerical_int.mw

## Why Latex generates non-printable characters?...

restart;
V:=x->piecewise(0<=x and x<=a,0,infinity):
ic:=f(x,0)=piecewise(0<=x and x<=a,A*x*(a-x),0):
pde :=I*h*diff(f(x,t),t)=-h^2/(2*m)*diff(f(x,t),x$2) +V(x)*f(x,t): sol:=pdsolve([pde,ic],f(x,t)) assuming a>0; Latex(sol) gives f \! \left(x , t\right) = \left(\left\{\begin{array}{cc}A x \left(a -x \right) & 0\le x \le a \\0 & \mathit{otherwise} \end{array}\right.\right)+\left(\Mapleoverset{\infty}{\Mapleunderset{n =1}{\textcolor{gray}{\sum }}}\! \frac{t^{n} \left(\textbf{proc} (U) \\ \textbf{option} \,operator,\,arrow; \\ \mapleIndent{1} r-1 st I \ast (-1/2 \ast h\hat{~}{2} \ast m\hat{~}{-1} \ast \mathit{diff} (\mathit{diff} (U,\,x),\,x) + \mathit{piecewise} (0&lex \, \textbf{and} \, x&lea,\,0,\,infinity) \ast U) \ast h\hat{~}{-1}\\ \textbf{end\ proc};\right)^{\left(n \right)}\! \left(\left\{\begin{array}{cc}A x \left(a -x \right) & 0\le x \le a \\0 & \mathit{otherwise} \end{array}\right.\right)}{n !}\right)  Notice, non-printable characters. I think it should have been \ast there but it gives st Maple 2020.2 and Physics 897. FYI, this is what latex() command gives  latex(sol) f \left( x,t \right) = \begin{cases}Ax \left( a-x \right) & 0\leq x \land x\leq a\\0 & \text{otherwise}\end{cases} +\sum _{n=1}^{\infty }{\frac {{t}^{n} \left( U\mapsto {\frac {-i \begin{cases}0 & 0\leq x \land x\leq a\\\infty & \text{otherwise}\end{cases} U}{h}}^{ \left( n \right) } \right) \left( \begin{cases}Ax \left( a-x \right) & 0\leq x \land x\leq a\\0 & \text{otherwise}\end{cases} \right) }{n!}}  Which compiles with no problem \documentclass[11pt]{article} \usepackage{amsmath} \begin{document} $f \left( x,t \right) = \begin{cases}Ax \left( a-x \right) & 0\leq x \land x\leq a\\0 & \text{otherwise}\end{cases} +\sum _{n=1}^{\infty }{\frac {{t}^{n} \left( U\mapsto {\frac {-i \begin{cases}0 & 0\leq x \land x\leq a\\\infty & \text{otherwise}\end{cases} U}{h}}^{ \left( n \right) } \right) \left( \begin{cases}Ax \left( a-x \right) & 0\leq x \land x\leq a\\0 & \text{otherwise}\end{cases} \right) }{n!}}$ \end{document} Thank you ## How to find triplets in Lie algebra at which Jacob... Asked by: Dear all I have Lie commutations for vectors e1, e2, e3, e4, e5, e6 as follow: [e1, e3] = e3, [e1, e4] = e4, [e1, e5] = e5, [e1, e6] = e6, [e2, e3] = -e5, [e2, e4] = e6, [e3, e5] = e6 for which the command Query("Jacobi") returns the false result, which means, the vectors are not closed under Jacobi's identity. How can I find vector triplets for which Jacobi's identity does not hold? Please find Maple file.Jacobi_identity.mw ## The solution of a PDE... Asked by: Dear all, I have a time-fractional PDE as follows. ( denotes Caputo fractional derivative with respect to t) for alpha=1, this is a classical PDE and the exact solution is given as follows (in a book) Question: 1) for alpha=1, I want to find the L2 errors and L∞ errors in a table. 2) for alpha=0.5, Can Maple find a solution (numeric or exact)? MY TRY: (MAPLE 2020.2) download the code.mw restart: with(plots): PDE:=diff(y(x,t),t)=y(x,t)*diff(y(x,t),x$3)+y(x,t)*diff(y(x,t),x)+3*diff(y(x,t),x)*diff(y(x,t),x\$2) ;

#c is an arbitratry constant
c:=4:
exact_sol:=(x,t)->-8*c/3*(cos ((x-c*t)/4))^2;

# I selected initial and boundary conditions as follows
IBC := { y(x,0)=exact_sol(x,0),y(0,t)=exact_sol(0,t),D[1](y)(0,t)=D[1](exact_sol)(0,t),y(1,t)=exact_sol(1,t)};

numeric_sol := pdsolve(PDE,IBC,numeric);

num3d:=numeric_sol:-plot3d(t=0..1,x=0..1,axes=boxed,
color=[0,0,y]);
exact3d:=plot3d(exact_sol(x,t),t=0..1,x=0..1,axes=boxed);
display(exact3d,num3d);

pdetest(y(x,t)=exact_sol(x,t),PDE,IBC);



## performance of pdsolve...

Hi

I have a system of pde that it is solved with pdsolve procedure.

This procedure takes a few time, but when I need to do plots, especially 3d plot the software takes a lot of time (several hours).

How can I make plots faster?
Thanks.

## When is evalDG needed when creating a tetrad etc i...

Given a metric, to compute quantities in the NP formalism one needs to specify a null tetrad. In the various examples in the help pages, sometimes the tetrad is specified simply as a list of 4 vectors, e.g., NT := [...] and sometimes evalDG is applied as in NT := evalDG({...]). Using the first format, Maple accepted NT as argument in NPSpinCoefficients but  NPCurvatureScalars(SpinCoefficients,NT) complained that the second argument wasn't a list of four vectors. When I used the second format, both commands returned the expected results. Why the difference?

RobinsonTrautmanSpinDG.mw

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