## How do I make the result of Result_Eva_GB_X2[3] :=...

I have attached the problem here. I need to say sorry, because I did not provide the whole code. So, automatically It will be error if you execute it.

If you see the attachement, you will see "Result_Eva_GB_X2[3] := []". It makes a problem if I want to make comparison. So I want the result of "Result_Eva_GB_X2[3] := []" is [0].

Actually the result of Result_Eva_GB_X2[3] := [] is complex number, because I did not want the complex I made select(x->is(0<x<1)....) to eliminate the complex number and negative result. So the question is How do I make the result of Result_Eva_GB_X2[3] := [] is [0]?

I have tried to add "Selection Statement (if)" (If the result is Undefined ([]) then Result_Eva_GB_X2[3] := [0]) But it can not work. Or maybe the selection statement that I made was wrong.

## How do I plot these three planes with the plot3d c...

I have the planes:

Plane 1: x + 3y - 5z = 0
Plane 2: x + 4y - 8z = 0
Plane 3: - 2x - 7y + 13z = 0

and I want to plot them in a 3d space with plot3d.

I tried to assign each plane to its own variable like this:

```P1 := x+3y: P2 := x+4y: P3 := -2x-7y:```
`plot3d([PlaneOne, PlaneTwo, PlaneThree], x = -8 .. 8, y = -20 .. 20, plotlist = true, color = [blue, red, green])`

`The planes plot, but they aren't showing correctly.`

`Here's how they should look, and here's how they look.`

`Please help. I don't know what I'm doing wrong`

## How do I change fonts on the Help pages?...

When I call up a Help page I see mostly boxes with question marks inside. If I copy the page into Word I get a badly formatted document in Canbria font. On other pages I get a font drop down box that indicates the page is in DejaVu Sans font and if I then change that to some font on my system (MAC 10.12.1) I get a perfectly readable document. Is there some preference, startup code or setting I can change to fix this annoyance?

## what happen with this numerical differentiation of...

 (1)

 (2)

 (3)

 (4)

when i try to get a numerical solution(using fdiff) for a second order derivative from a numerical diff ecuation procedure i got "index out of range". however, it perfectly works with a first order derivative. what's thwe matter there?

thankyou very much..

## Lookup value from list...

Hello

My question regarding a lookup function is enclosed in the file.

lookup.mw

## How do I solve the problem that I have attached? ...

I have upload the attachment here. in this problem I want to find the comparison. Please check it and please tell me the correction

Is there some way to delete a task from my Tasks palette

At some point I created "My second palette" is there a way
to delete individual items from this palette and how are tasks

Any help appreciated, Thanks! Les

AB44.mw

## Equate two expressions...

Hello!

Hope everything fine with you. Please check the following program

restart; a := 0; b := 1; Rd := .5; Ra := .2; Nc := .6; e := .2; Nr := .3; H := .9; Digits := 20;
with(LinearAlgebra);
L[0] := 1; L[1] := a+1-x;
M := 4; K := 1;
for n while n <= M do
L[n+1] := expand(-((x-2*n-a-1)*L[n]+(n+a)*L[n-1])/(n+1))
end do; printlevel := 2;
for m from 0 while m < M do
for n to 2^(K-1) do
psi[n, m] := simplify(sqrt(m+1/2.)*2^((1/2)*K)*(eval(L[m], x = 2^K*x-2*n+1)))
end do
end do;
f1 := simplify(sum(sum(c[p, q]*psi[p, q], q = 0 .. M-1), p = 1 .. 2^(K-1)));
u := collect(f1, [x], recursive);

u := -3.5276684147527874541*c[1, 3]*x^3+(4.4721359549995793928*c[1, 2]+21.166010488516724724*c[1, 3])*x^2+(-3.4641016151377545871*c[1, 1]-13.416407864998738178*c[1, 2]-34.394767043839677677*c[1, 3])*x+c[1, 0]+3.4641016151377545871*c[1, 1]+7.8262379212492639373*c[1, 2]+14.992590762699346680*c[1, 3]

f := 1+sum(A[i]*(x^(i+1)-(i+1)*x), i = 1 .. M-2)

f:=1+A[1]*(x^2-2*x)+A[2]*(x^3-3*x)

I want to equate the like powers of "x" in f ( mention as red) and u ( mention as red) for any values of M make a system of equations as

Eq[1]:=-3.5276684147527874541*c[1, 3] = A[2];

Eq[2]:=4.4721359549995793928*c[1, 2]+21.166010488516724724*c[1, 3] = A[1];

Eq[3]:=-3.4641016151377545871*c[1, 1]-13.416407864998738178*c[1, 2]-34.394767043839677677*c[1, 3] = -2*A[1]-3*A[2];

Eq[4]:=c[1, 0]+3.4641016151377545871*c[1, 1]+7.8262379212492639373*c[1, 2]+14.992590762699346680*c[1, 3] = 1;

and solve them for any values of A[1] and A[2];

Also attached the program Equate.mw

With my best regards and sincerely.

School of Mathematical Sciences
Peking University, Beijing, China

## Variable with Unit to power (e.g. 2) without alter...

Im attempting some very basic calculations where numbers are stored in variables with correct units. However i wish to take a variable to the power 2 without altering it's unit. This is a really easy but strange calculation to make which is why i guess Maple is having trouble with it.

e.g. I have a variable A with a number 4 stored inside with unit in Meters. I want to take A2 = 16 meters and and not A2 = 16 meters2

Is there a function or way to select the base number without having to write an entire line about it?

convert(A,'unit_free')^(2)*Unit('m')

can do the trick but i believe there has to be an easier, less complicated, way to achieve this?

## How to do symbolic calculation in GR...

Hello everybody,

In the linearised theory of gravity, I want to do some symbolic calculations.  First, I need to set that:

Then I want to see how the Christoffel symbols will change by putting the above in this:

Any hint someone?  I really appreciate the help for learning the Physics package.  Thank you in advance.

Mario

Error, More than two dependent variables, please indicate the desired scene

## Error in using Worksheet:-Comparator ...

Hi everybody,

I am working with Maple 2015.2 ; system = OS X El Capitan
I would like to compare the outputs of two files by using  the Worksheet:-Comparator command

OriginalFile.mw file contains this single instruction
> a:=1;

ModifiedFile.mw contains this single instruction
> a := 2;

Both us are located on my desktop, which is also my current directory in the worksheet from which I am going to run the comparison.

MyDir := cat(currentdir(), "/Desktop/");
OriginalFile := cat(MyDir, "OriginalFile.mw"):
ModifiedFile := cat(MyDir, "ModifiedFile.mw"):

# to verify that all is going well I use these two commands
# Worksheet:-DisplayFile(OriginalFile):
# Worksheet:-DisplayFile(ModifiedFile):

Running the  command  Worksheet:-Comparator(OriginalFile, ModifiedFile) returns me error messages :
The first one is  (after having selected  "compare" and next "run" in the Comparator Maplet)

and the second one (after having cliked ont the "OK" button" on this alert window)

Note that the same thing happens if I use Worksheet:-Comparator() and select the two files with the browsers

## How do I solve the problem that attached? ...

How do I solve the problem that attached? Please give me the correction. thank you

## A question about the "Explore" command...

Greetings!

Strange things happen with the "Explore" command! Let's say I want to plot the function F(x)= a*x. When I am writing:

>Explore(plot(a*x,x=0..10),parameters=[a=0..2]) ;

everything is OK, but when I use:

>F:=a*x;
>Explore(plot(F,x=0..10),parameters=[a=0..2]) ;

the initial frame is correct but when I try to move the parameter cursor, the plot dissapears.

Any ideas what is wrong and how I can fix this?

## How to execute an "exported as maplet" worksheet ...

Hi everybody,

I write a worksheet which contains thesimple code provided in ?Maplets[Button] :

with(Maplets[Elements]):
maplet := Maplet(["Select one:", ......])
Maplets[Display](maplet):

As mentioned in ?MapleViewer it is possible to export a worksheet in a .maplet file (I use Windows 7) and to execute it by double clicking on the corresponding icon.
I proceeded as explained in the help page
But double clicking does not work with me : a "User Interface Customization System" window opens and shuts after a few seconds without displaying the expected maplet

(right click + open with and select mapleviewer.exe shows that mapleviewer.exe does exist, so the issue does not likely come from an incomplete Maple installation).

I tried a few variants of the worksheet, such that
with(Maplets[Elements]):
Maplets[Display](Maplet(["Select one:", ......])  ):

or even
Maplets[Display](Maplet(["Select one:", ......])  ):