## How to convert string input to symbol?...

I run the following working maplet:

Where "muutujad" is a procedure I defined and which returns the three inputs in the form [TF1,TF2,TF3].

It works fine, but if I insert "theta" as input, it of course stays in the string form, not Θ. Even if I copy the symbol and paste it in the textfied, it doesn't accept the symbol. Is there any way I can convert the text input to actual symbol?

## How to use function in boundary condition? ...

Hi !

I am trying to solve a pde with initial/boundary conditions, in the numeric mode. It works very well when I provide 3 numerical conditions : 1 initial condition (uniform distribution at first), and two boundary conditions.

Now I want to switch the initial condition to a function of r. It's a polynome I obtained after interpolation of another result. I tested it and the function interp20(r) works. But the pdsolve doesn't seem to evaluate the function, when it comes to start the procedure and pdsolve doesn't return a module as it should, although it doesn't send any message error.

You can see the code following, with the error messages I get.

Is it strictly impossible to use a function as an initial condition ?
Is it just a problem I could solve by converting the function or its result to something else ?
Is float the right type of input ? For example, if I write a:=283.15, is it a float ?
Have you already had similar problems ? How did you solve them ? Where could I find working code examples on this ?
Could I solve this problem with non-uniform initial condition with another Maple function ?

Then you very much for your help !

## indefinite integration...

I have a problem about the integration of a function. The maple returns mathematical form of the given command

the function is

fn :=(-4.079067798*10^(-16)+3.422708023*10^(-16)*I)*(3.363377947*10^(-11)+5.977507284*10^(-12038)*I+(3.363377947*10^(-11)+4.678081798*10^(-22)*I)*erf(1.664331698*10^15*qq-0.2503507367e-1-4.649313602*I)) *exp(-2.77*(qq/(tau*tau))^2)*exp(-I*w0*qq)*exp(-(ss-qq)/T_pop)

qq is the integration variable qq=-inf..ss

w0=10^15

tau=10^(-15)

T_pop=30e-15

## How to pdsolve heat transfer equation?...

Hi everyone,

I am trying to solve the equation of heat tranfer, time dependent, with particular Initial and boundary conditions but I am stuck by technical problems both in getting an analytical solution and a numerical one.

The equation

the equation.

I defined a and b numerically. domain is : and I defined surf_power numerically.

The initial condition is : , T0 defined numerically

The boundary condition is : , because it has a shperical symetry.

To me, it looks like a well posed problem. Does it look fine ?

Problem in analytical solution :

It doesn't accept the boundary condition so I only input the initial condition and it actually gives me back an expression that can be evaluated but it never does : I can't reduce it more than an expression of fourier which I can't eval. The solution :
The solution calculated in (0,0). I was hoping T0...

Are you familiar with these problems ? What would be the perfect syntax you would use to solve this ?

The numerical solution problems :

Sometimes it tells me that my boundary condition is equivalent  to 0 = 0, and I don't see why. Some other times it tells me I only gave 1 boundary/initial condition even if I wrote both. Here is what I wrote for example :

(because it kept asking me to add these two options : 'time' and 'range')

Are you familiar with these problems ? What would be the perfect syntax you would use to solve this ? I must at least have syntax problems because even if I keep reading the Help, it's been a long time since I used Maple.

Thank very much for any indication you could give me !

Simon

## wrong format when copy to notepad from maple...

for i from 0 to 3 do print("rawData[", i, "] = new double[] { ", hello(i+1), ",", data[i+1], "};") end do

wrong format after copy to notepad from the maple 15

do not know why it insert a empty line, and make "};" in another line

and there is unexpected "

wrong format example:

"rawData[", 0, "] = new double[] { ", 73.25, ",", 0.1510425143,

"};"
"rawData[", 1, "] = new double[] { ", 73.15, ",", 0.3974080269,

"};"
"rawData[", 2, "] = new double[] { ", 72.85, ",", 0.4661517269,

"};"
"rawData[", 3, "] = new double[] { ", 73.25, ",", 0.3974080269,

"};"

expected format:
rawData[0] = new double[] { 25.0, 20.0 };
rawData[1] = new double[] { 27.0, 34.0 };

## How to solve delay differential equations with Map...

How to solve delay differential equations with Maple?

Example:

diff(x(t),t) = 3*x(t)^2 + 0.3*x(x-0.03)

## Maple 15 numerical evaluation of integrals cannot ...

I use Maple 15 to calculate some (nasty) integrals at my university. Because our university also offers a server on which I can run my Maple program, I would like to do that. (instead of occupying a workspace). But at the computer on my workspace the integrals are evaluated fine, but on the server the integrals are just returned with no numerical evaluation.

I constructed a MWE to look where it goes wrong. I set the printlevel to 25 so I could see what was going on. The MWE was suprisingly simple, on both machines (via ssh) I executed within maple:

This of course would normally just give 2*sqrt(2). On my workplace-pc it worked fine and it found 2.828427125. The server just returned the integral. After looking at the steps, they where both exactly the same until the following part:

Workplace-PC:

General_flags := {_NoNAG, _DEFAULT, _NoMultiple}

NAG_methods := {_d01ajc, _d01akc, _d01amc}

Method := _DEFAULT

HFDigits := 15

-12
HFeps := 0.1 10

-9
HFeps := 0.5000000000 10

oldEvents := overflow = default, division_by_zero = default

callNAG := true

fcns := {}

result := 2.82842712474618807

Server:

General_flags := {_NoNAG, _DEFAULT, _NoMultiple}

NAG_methods := {_d01ajc, _d01akc, _d01amc}

Method := _DEFAULT

HFDigits := 15

-12
HFeps := 0.1 10

-9
HFeps := 0.5000000000 10

oldEvents := overflow = default, division_by_zero = default

callNAG := true

fcns := {}

overflow = exception, division_by_zero = exception

It seems that the server has a problem with the singularity and thus throwing an exception, but I just don't get why. The Maple-versions are both the same.

Does somebody know what this could be?

## Numerical solution of intersection of two curves o...

Hello I am a Maple 15 user and I am using the command fsolve to solve for the intersection of two curves over a specified interval in x, namely from 0 to the lim defined in the Maple document. The specified interval contains asymptotes and when I specify the full interval only one of the three solutions is returned even if I can see that there are three distinct solutions by looking at the plot of RHS and LHS. Should I use another technique to find the solution or is my implementation of fsolve command wrong?

 (1)

 (2)

 (3)

## optimal control problem...

Hi there,

Is there a way in which i can solve the following optimal control problem numerically with Maple?

dH/dt=λ-µ H-(1-u1)β H V+δ I,

dI/dt=(1-u1)β H V-σ I,

‎dV/dt=(1-u2)k I-γ‎V,

dλ1/dt=-1+λ1µ+β‎‎V(1-u1)(λ1-λ2),‎

dλ2/dt=λ1δ+λ2σ-λ3(1-u2)k‎,‎

‎dλ3/dt=β H(λ1-λ2)(1-u1)‎‎+λ3γ.

where

u1=βHV(λ1-λ2)/A1,

u2=-λ3kI/A2,

σ = α + δ,

and

H(0)=1.7*10^8,    I(0)=0,    V(0)=400.

λ=5*10^5,    µ=0.003,     β=4*10^(-10),    α=0.043,    δ= 0.2                  k=6.24,       γ‎=0.65.

A1=900, A2=1000.

Thank you all for reading.

Aylin

## export plot as gif file empty...

i am trying to export an animated gif file but the export windows freezes and exports an empty file with zero bytes

the animation was created by: display(map(p, convert(A(() .. (), 2), list)), insequence = true)

i have tried to give maple some time (2-3 hours) and i even tried to restart the computer and lauch maple and try to export it but it didnt worked

how can i export it or how can i plot the using commands

## Maple 15 on Windows and Ubuntu in a dual boot syst...

Hello,

Is it possible to use Maple 15 Student Edition with the same license information and purchase code both on Windows and Ubuntu?

I did a few Windows reinstalls (guess about 3) hence I used the same purchase code to activate the license that many times. Today I tried installing and using Maple 15 on Ubuntu 12.04.3 LTS 32-bit and to my dismay the license manager said, "Not enough activations left on this account." Furthermore, I have exhausted my download links and would like to know how many times Maple 15 can be activated and if the download links can be refreshed?

Thanks

## Problems plotting flow lines of a vector field...

I'm trying to display some flow lines for a vector field. The vector field I have is:

What I put into Maple is:

I've tried this with a number of points, but I always get an error message along the lines of:

"Error, (in Student:-VectorCalculus:-FlowLine) cannot determine if this expression is true or false: (2.*(1)(0)-4.)^2+(-2.+4.*(1)(0))^2 < 0.9e-9"

Could someone please shed some light as to what's going wrong for me? I would be very grateful for any help.

Thanks.

## over detemined system...

i have got alot of mixed and high degree derivatives. For example:

u[x]*u[x,t]*eta[x,t]+u[]^2*u[x]*eta[x]+kis(x,y)u[x,t]^2*u[]+eta(x, y)*u[]*u[x]^2+ksi[x,t]*u[x]^2*u[x,t]+......

like this alot of terms

my question is how can i solve divided by the derivative of the u(x,t) partial differential equations system and so  how can i find eta(x,t,u) and ksi(x,t,u)