Unanswered Questions

This page lists MaplePrimes questions that have not yet received an answer

Dear all,

I have the following metric

Is there any way to make the terms dt dphi and dphi dt not symmetric?

Denis

 

 

I was wondering why Maple hangs on this first order heat pde (waited for more than 15 minutes)

pde:= diff(u(x,t),t)= diff(u(x, t), x$2) - 9*diff(u(x,t),x);
bc:=u(0,t)=0,u(1,t)=0;
ic:=u(x, 0) = exp(45/10*x)*(5*sin(Pi*x) + 9*sin(2*Pi*x) + 2*sin(3*Pi*x));
#infolevel[pdsolve]:=3;
pdsolve([pde,ic,bc],u(x,t))

It shows it hangs here:

Trying HINT = _F1(x)*_F2(t)
                           Trying given functional HINT ...
                     Third set of solution methods successful

Mathematica solves this very quickly and returns

heqn = D[u[x, t], t] == D[u[x, t], {x, 2}] - 9*D[u[x, t], x];
ic = u[x, 0] == Exp[45/10 x]*(5 Sin[Pi*x] + 9 Sin[2*Pi*x] + 2 Sin[3*Pi*x]);
bc = {u[0, t] == 0, u[1, t] == 0};
sol = DSolve[{heqn, ic, bc}, u[x, t], {x, t}]

I am asking becuase Maple normally have no problem with such PDE's so I was surprised it hangs on this one and was trying to find out why.

Other than using infolevel[pdsolve]:= what other tools should one try to debug where exactly it hangs and why?

Maple 2019, Physics V 350

The help for the package Differential Geometry suggests one way to create an anholonomic frame, but the method suggested assumes one knows the frame and can write it in the coordinates of the manifold, and use this representation to compute the structure equations. It is useful to turn this problem around: suppose I know the structure equations but I do not know the frame, how do I correctly enter this in Maple so that later computations are correct?

 

Here is an example:

with(DifferentialGeometry): with(LieAlgebras):
DGsetup([x, y], R2):          
Fr := [A, B]; StructureEquations := [[A, B] = a(x, y)*A];
LD := LieAlgebras:-LieAlgebraData(StructureEquations, Fr, M);
DGsetup(LD, verbose):

that creates the Lie algebra M. I thought it would produce the manifold M whose frame {e1,e2} (or {A,B})) obeys the structure equations. But it does not. Indeed, the simple example

LieBracket(e1, f(x, y)*e2);

returns

f(x,y) a(x,y) e1.

The extra term where e1 differentiates f(x,y) does not appear. Just to be clear, the correct answer is

f(x,y) a(x,y) e1 + e1[f] e2.

 

How should I correctly setup this manifold?

 

Our company is producing a kind of smart electronic drying rig Vinadry. We want to apply physical formulas to calculate the lift and tension of the drying rigs when operating. By this Vinadry drying rig we want to design it as a pulley system but can control it via electric buttons. Hence I want to consult people how I should calculate accordingly

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

I am installing maple 2019 on Linux 64 bit. I used the option

--mode text

The installer has not proceeded after answering Y to the following. 

Activate Maple 2019 now (requires an Internet connection). [Y/n]:

Any suggestions? 

I can  this equation.

CV.mw
 

restart; c__v := 1.2; `τ__q` := 8.5*10^(-12); `τ__T` := 90.0*10^(-12); rho := 1000; k := 10

1.2

 

0.8500000000e-11

 

0.9000000000e-10

(1)

k*(diff(T(x, t), x, x))+k*`τ__T`*(diff(T(x, t), t, x, x)) = rho*c__v*(diff(T(x, t), t))+(diff(T(x, t), t, t))*c__v*rho*`τ__q`+(1/2)*c__v*rho*`τ__q`^2*(diff(T(x, t), t, t, t))

10*(diff(diff(T(x, t), x), x))+0.9000000000e-9*(diff(diff(diff(T(x, t), t), x), x)) = 1200.0*(diff(T(x, t), t))+0.1020000000e-7*(diff(diff(T(x, t), t), t))+0.4335000000e-19*(diff(diff(diff(T(x, t), t), t), t))

(2)

Boundary condition:

T(0, t) = 300; T(10, t) = 300

#####################################

INITIAL CONDITIONS:

 

T(x, 0) = 300; (D[1](T))(x, 0) = 0, (D[2](T))(x, 0) = 0

(D[1](T))(x, 0) = 0, (D[2](T))(x, 0) = 0

(3)

``


 

Download CV.mw

 

 

i) D(X,Y) , D(X,Z) ,D(Y,Z) COVARİANT DERİVATİVE ?

İİ) [X,Y] LİE OPERATOR ? 

İİİ) R(X,Y)Z = D DZ - DDZ - D[X,Y] Z

My Maple Worksheets (not Maple Documents) have lots of explanetory Text blocks [..... surounding executable Math blocks ([> ..... I often insert mathematical symbols, most commonly subscripted variables, in these Text blocks.  For a simple example, consider the text block entered as

[This is a test of a subscripted variable "CTL-R" h__0 "CTL-T" in a text block.

The "CTL-R" (quotes are not actually entered) is the short cut to go into math mode, and "CTL-T" exits math mode and returns to text mode and the double underscore produces an atomic subscripted variable.

The text block actually will look like

[This is a test of a subscripted variable h0 in a text block.

The problem occurs when I reexecute the worksheet. The Text block actually produces output labeled with an equation number. For my simple example above the Text block becomes

[This is a test of a subscripted variable h0 in a text block.

[                                              h0                                                   (1)

 

where the two lines started by [ are actually merged with one expanded [ for the Text block with its output. To get rid of the unwanted output, I have to put my curser over the h0 that is in the Text body (not the output h0) and hit "Shift-F5". The output h0 with its equation number disappears.  If there are a number of simple math expressions in a text block, I have to process them one at a time with "Shift-F5". This takes up a lot of time. With earlier Maple versions (~2015 or earlier) I used to fly through Text blocks using the shortcuts "Ctl-R" and "Ctl-T" and these Text blocks produced no output when the worksheet was reexecuted. 

Starting with Maple 2016 I could enter math expressions in Text blocks using the shortcuts, but I could not copy and paste  a Text block with inline math expressions without the expressions becoming "live" in the copied block.  Starting with Maple 2017 all my Text boxes with math expressions began executing the math and producing output.

I gave up on Maple 2017 and 2018.  I have finally made the jump from Maple 2016 to Maple 2019, in part, because I finally discovered the "Shift-F5" trick to make math expressions in a Text block inactive.

Does anyone know how to make the default behaviour of Maple with math expressions in a Text block to be "Don't execute the math and produce output in the Text block"?

I would post an actual example worksheet, except I have never been successful whenever I have tried to upload a worksheet. I hope my description above is adequate.

Any help will be greatly appreciated.  Neill Smith

 

 


 

restart; with(VectorCalculus)

r := `<,>`(sin(t), cos(t), t)

Vector(3, {(1) = 0.2739493386e-115+0.2739493386e-115*I, (2) = 1.0-0.7504824014e-231*I, (3) = t})

(1)

``


what??

Download problem.mw

How I can take Laplace Transform from equation.

Thanks

LAPLACE

The worksheet below rolls an ellipse along the y axis with constant energy.

How can the physics be enhanced to roll the ellipse along a non-linear curve (e.g. a sine curve) with constant energy?

EllipseRoll.mw

i have a diff equation(in photo last one)ehich code coulde solve it?

 

Earlier smoothly working generation of normal distribution in v. 2019 unexpectedly shows the error:

RandV  := Statistics[RandomVariable](Normal(0, 1));
Statistics[Sample](RandV, 10);

Error, (in p) unable to convert Float(undefined) to an integer

 

Help create file Excel in ExcelTools, but error row 564?

thu_file.mw

Please help me? 

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