## How to remove all output from a worksheet?...

I just noticed with chagrin that one of my favorite menu commands, Edit -> Remove output -> From worksheet, is missing from Maple 2019's Standard GUI. Is there a keyboard command or toolbar item to replace it?

## A possible bug in Maple 2019: a strange problem of...

Hello everyone, Greetings!

I am facing a really strange problem. I need to write an expression, however, maple out of nowhere assigns values to the variable used. only to those which are written inside sin (). In previous versions the out put is fine. Is there a new way to write expressions in maple 2019? I am not sure.

 >
 > 96*sin(2*beta*y)*cos(2*beta*y)*beta^4 + 96*sin(2*beta*y)*beta^4
 (1)
 >

## How to automatically cancel any common factors on ...

I have encountered the situation frequently where I want to simplify an equation by cancelling out terms on both sides.  I have tried simplify() with a variety of assumptions(J,L>0,etc) and I haven't been able to get it to work.  On a simple equation, one can use 'solve' however there are situations where solve doesn't work and I just want to simplify the equation not solve it.

The script below shows the situation.  I cancel out JL and the complex exponential by manually identifying that they are common factors.  Is there an automatic way of doing this type of simplification?

If I use expand() it clearly shows the common factors on both sides but I haven't found the command that removes any common terms.

 >
 (1)
 >
 (2)

 >
 (3)

 >
 (4)
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## Maple procedure to find the solutions to a cubic...

Hi I need to write procedure to find a cubic equation... anyone could help me ...?

## How to remove summation from both sides?...

At a point in a worksheet I end up with an equation that has summations on both sides.  The range of summation is the same but the summands are different.  I want to remove the summations from both sides, keeping the equation with just the summands. How can this be done?  The only way I have found is to manually select each summand with the mouse and paste it into a new line which breaks the 'automation' of the script.

## simplify expression to complete derivative...

This

`expr:='1/r^2*diff(r^2*diff(v(r),r),r)'`

gives

And when evaluated second time it gives

`expr`

The question is, how to put expr back to its original form shown at the top?

I tried simplify, combine, etc.. but nothing puts back to same form.

The reason I am asking, is that I need put more complicated expression in form that resembles when I am looking at in textbook. For an example, the Laplacian

```VectorCalculus:-Laplacian(u(r,theta,phi),'spherical'[r,theta,phi])
```

But the above should be the same as

So I figured if I can rewrite each term to look like in the shorter version above (complete derivative version), it will be easier for me to compare what Maple gives and the text book shows,

ps. I found that the following command in Maples gives a little clearer Laplacian, but it is still not as simplified as the book but it is better than using VectorCalculus:-Laplacian

```Physics[Vectors]:-Laplacian(u(r,theta,phi));
```

At least this has each term a little more seprated.

## Why the temperature is so high when start Maple 20...

If I have checked the Editable button just below the working window, then the temperature would be very high in the next time when I start Maple 2019. I do not what is going on. But when I unchecked the Editable button, and wait for several seconds, then the temperature and the load of my laptop are on the normal state.  Is this a bug for Maple 2019? My OS is Debian Stretch, that is,

\$ uname -a
Linux debian 4.9.0-9-amd64 #1 SMP Debian 4.9.168-1 (2019-04-12) x86_64 GNU/Linux

## How to prevent immediate evaluation of trig functi...

When typing

```z:=exp(I*2*Pi/3);
convert(z,'sincos')```

Maple evaluates the intermediate result which is cos(2*Pi/3)+I*sin(2*Pi/3) and  gives

Is there a way to tell it not to do this? I'd like to see the result as when typing

```'cos(2*Pi/3)+I*sin(2*Pi/3)'
```

Is there an option or method to tell Maple not to immediate evaluation in the above? it can do evaluate next time the expression is used.

## Initialise simple model...

Dear all,

I am totally new to maple and would like to get an understanding for the "language" and how to work with maple. Thats why I tried to get a simple model from Mathematica into Maple, however, unfortunately, I am not able to initialize the plot I want to generate. Hence, I am wondering if someone could please help me here. My code looks as follows:

```P[t] := a*ED[t - 1] + P[t - 1]

ED[t] := DC[t] + DF[t];

DC[t] := c(P[t] - P[t - 1])

DF[t] := b(F - P[t])```

my initial conditions are:

```a := 1
c := 0.75
b := 0.2
F := 100
P[0] := F
P[1] := F + 1
```

Now I would like to see how P[t] develops for t from 0 to 100, but I get the error "Error, (in Plot) Plot([ED[t-1]+P[t-1], t = 0 .. 100]) is not a valid command; see the plot help page" However, I am not able to get a grip on the helppage information. Hence I would be very glad if someone could help me here please.

Best, Alex

## pdsolve gives division by zero...

Should Maple handle this error internally and may be give no solution if it can't solve it instead of this  error?

When setting boundary condition to zero, maple gives error below. Heat PDE in a sphere. No angle dependency. Only the radial part.

```unassign('r,u,t');
pde:=diff(u(r,t),t)= 1/r*diff(r*u(r,t),r\$2); #Laplacian in spherical
ic:=u(r,0)=1;
bc := u(1,t) =0;
pdsolve([pde,ic,bc],u(r,t),HINT =boundedseries(r=0)) assuming t>0
```

Error, (in assuming) when calling 'ln'. Received: 'when calling 'ln'. Received: 'numeric exception: division by zero''

Adding assumptions such as 0<r,r<1 did not help.

Physics version 348. Maple 2019 on windows 10. Is there something I am doing wrong?

## How to change the styles of Help System pages?...

Maple has powerful tools to manager styles of its documents. Similar to word processors, it is possible to set up font and paragraph options. Unfortunately, the styles of Help System, as I understand, are completely unchangeable. Meanwhile, it makes sense to improve the view of Help pages. Say, Help’s hyperlinks are pale and unpleasant  for eyes. Maybe, are there some hidden options for changing Help styles?

## on display of eval(diff)...

Why does Maple display eval(diff(f(r),r),r=C)=0;  differently when C is a number?

```unassign('f,C,r');
eval(diff(f(r),r),r=C)=0;
eval(diff(f(r),r),r=5)=0;
```

I wanted the first one to display the same as the second one. First one looks confusing. it looks like taking derivative w.r.t to C. Is there a way to make the first one look like:

## New text line problems...

Hi,

I am having issues with switching from math mode to text mode, when it comes to adding a new line of text under a line of math mode, without evaluating the math. In a previous version of Maple (not sure witch one, probably Maple 2018), I would switch from math mode to text mode by using the shortcut "command + T", followed by hitting the "->" button on the keyboard and then hit enter to start a new line in text mode. But this does not work in the latest version of maple. Does anyone have a solution for this problem?

Also, is there a way to remove the "toolbox" (i.e. "solve for"/"expand"/"simplify"/"isolate"/etc.), so it only appears when right-clicking on the expression you want to edit?

It's no secret that I liked the older versions of Maple, but I'd very much appreciate some assistance with the 2019 version!

Kind regards,

Lisa

## Can isolve be used with irem?...

I am trying to get this to work

`{seq(isolve({a = k, irem(a*b, 10000) = 2391}), k = 1 .. 9999)}`

but am not getting any answer. One solution is irem(297*9503, 10000).

## How to do dchange OLD=NEW where NEW contains para...

I am learning how to use dchange in Maple. I can do  something as dchange(x=t^2) OK, but I need to do dchange(x=t^n) where "n" is meant to be a parameter that I can later use subs on to set it to any number I want.  But I do not know how to tell Maple that "t" is the new variable and that "n" is meant to be used as constant or parameter.

As an example, this works

```n:=2;
ode:=x^2*diff(z(x),x)=0;
PDEtools:-dchange({x=t^n},ode,{t})
```

But this does not work

```n:='n';
ode:=x^2*diff(z(x),x)=0;
PDEtools:-dchange({x=t^n},ode,{t});
subs(n=2,%)
```

It used "n" above as new variable. So the dependent variable which was z(x) became z(t,n).

So I need to tell Maple that "t" is the new variable only and not "n" as well.

Is it possible to do this in Maple?

Maple 2019 on windows.

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