## contours from an array of points using surfdata in...

I found from this forum that to plot a 2D array of points use can be made of the Maple procedure surfdata.

Does anyone have suggestions on how to plot contours in (preferrably) Maple 16 or Maple 17?

I tried the following

Output := Array(-10 .. 10, -10 .. 10, proc (i, j) options operator, arrow; i^2+j^2 end proc):
F := proc (x, y) -> x^2+y^2 end proc:
surfdata(Output, color = F, dimension = 2);

but "the option dimension = 2" is a Maple 18 addition.

Ideally, I would like also to be able to plot contours with options found in the procedure
contourplot

## RootOf Error needing to be dispatched to the engin...

Hi, i encountered this, error, and the link to the help page was broken.

Error, (in RootOf) expression independent of _S000100

## Why am I getting Line-Printed Output instead of a ...

I don't recall ever changing any settings in my copy of Maple 16. But for some reason, I tried to make a plot and it spit out line-printed output rather than a regular plot.

How do I change this back? I have no use for line-printed output.

 Nitrogen Nucleus Second-Order Energy Shifts                    |                                                                              +                                                                     HHHHH 6e-08                                                               HHHHH        +                                                            HHHHHH          4e-08                                                     HHHHHH                 +                                                  HHHHHH                      +                                           HHHHHHH                          2e-08                                  HHHHHHHH                                  +                           HHHHHHHHHH                                         +             HHHHHHHHHHHHHHH                                                  *************************************************************************** 0 +              1    HHHHHHHHHH2HH           3              4              5   +                               HHHHHHHHH                                    -2e-08                                    HHHHHHHH                               +                                              HHHHHHH                       -4e-08                                                 HHHHHH                    +                                                         HHHHHH               +                                                              HHHHH         -6e-08                                                                HHHHH      +                                                                       HHH

## How to write the solution of a system of equations...

Hello,

I am solving a simple system of algebraic equations in a "for" loop. I would like to write all the values of solutions to a matrix, but I only get the symbols. Here is my code:

```A:=1:E:=0.1:L0:=<5,5,5,5>:m0g:=0.05:u:=<-5/4,-1/4,-3/4,-1/4>:v:=<-1/2,-3/2,1/2,1/2>:w:=<0,1,0,-1>:
Force:=Matrix(m,2);
for i from 1 to m do
r1||i:=H||i*L0(i)/(A*E)+H||i/m0g*(arcsinh(V_A||i/H||i)+arcsinh((m0g*L0(i)-V_A||i)/H||i))-sqrt(u(i)^2+v(i)^2);
r2||i:=V_A||i*L0(i)/(A*E)*(m0g*L0(i)/(2*V_A||i)-1)+H||i/m0g*(sqrt(1+((m0g*L0(i)-V_A||i)/H||i)^2)-sqrt(1+(V_A||i/H||i)^2))-abs(w(i));
rozw||i:=fsolve({r1||i, r2||i}, {H||i,V_A||i},H||i=0..1);Force(i,1):=H||i;Force(i,2):=V_A||i;subs(rozw||i,Force(i,..));
end do:
evalf(Force);
```

Iza

## How can I find the min and max of modulus of a com...

Let be the number z so that |z+3-2*I| + |z-3-8*I| = 6*sqrt(2). Find min and max of the modulus of z. How can I find min and max of modulus of z with Maple.

## DifferentialGeometry...

How to manually switch frames in the DifferentialGeometry package? (Example: Help_Differential geometry_lesson2_exercise 4). Thank you

## in FileTools:-Text:-CountLines) permission denied,...

Maple 16 code

N1 := FileTools[Text][CountLines](g)

I encounter an error message

in FileTools:-Text:-CountLines) permission denied

What  went wrong ?  This never happened before

I  re install  Maple 16, the same error persists.

Martin

 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >

## How do I get rid of the error?...

`Download 2222222222222222222.mw`

```> restart;
> A[0] := 10^(-3); a := 10^5;
> sys := diff(R(theta), theta) = A[0]*exp(2*mu(theta))*sin(theta)/(2*a), R(theta) = 2*exp(-2*mu(theta))*(1-(diff(mu(theta), `\$`(theta, 2)))-cot(theta)*(diff(mu(theta), theta)));
> cond := R(0) = 10^(-5), mu(0) = 118.92, (D(mu))(0) = 0;
> F := dsolve({cond, sys}, [R(theta), mu(theta)], numeric);
> with(plots);
> odeplot(F, [theta, R(theta)], 0 .. 3.14, color = black, thickness = 3, linestyle = 4)
> odeplot(F, [theta, mu(theta)], 0 .. 3.14, color = blue, thickness = 3, linestyle = 1)```

After last two lines maple writes:

Warning, cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up

And gives me empty plots. I can't figure out where an error can be. Some things I noticed:

Maple doesn't calculate the system before and after zero. If I change the range from 0..3.14 to -10..10 or to 0.00001..0.00001, it gives me 2 errors for 1 plot.

Also if I change the condition mu(0) = 118.92 to mu(0) = 1 or mu(0) = 50 or mu(0) = 80, it works. After ~80 it gives an error. I can't imagine where could appear a division by 0 or some other mistake.

## Can this Jacobi Differential equation be solved?...

I have been trying to find a solution for the equation below. Is there a non numerical explicit solution?

 (1)

 (2)

 (3)

 (4)

 (5)

 (6)

 (7)

 (8)

 (9)

 (10)

 (11)

## How do I solve the example from Maple Help LPSolve...

When I try the example from Maple Help for LPSolve (I use Windows)

with(Optimization);
LPSolve(-4*x-5*y, {0 <= x, 0 <= y, x+2*y <= 6, 5*x+4*y <= 20});

I do not get the same solution like in the example: [-19., [x = 2.66666666666667, y = 1.66666666666667]]

Warning, problem appears to be unbounded
[0., [x = HFloat(0.0), y = HFloat(0.0)]]

My Professor uses the same version, but with Linux and do not have such problems. Why my installation does not solve the standart Help example?

Thank you

## Maple fails to simplify negative power...

f1:=(1/s^2)^N;

Maple failed to convert it into  f1:=s^(-2N);

## Solve PDE by pdsolve, how to interpret answer?...

Hi!

Tried to solve the PDE below (q and p are time-dependent variabels, q(t),p(t)):

```pde := diff(rho(t, q, p), t) = -(diff(rho(t, q, p), q))*p+(diff(rho(t, q, p), p))*(2*q+2);

pdsolve(pde, rho(t, q, p));
```

`rho(t, q, p) = _F1(p^2+2*q^2+4*q, -(1/2)*sqrt(2)*arctan((q+1)*sqrt(2)*(1/sqrt(p^2)))+t)`

But I'm not sure how to interpret the result. I understand that  _F1 is an arbitrary function, but then I get confused with the comma? I thought that I'd get a function of q and p, where they depend on t.

Best regards
Sannis

## How do I solve a first order linear PDE with two t...

Hello!

For the last couple of days I've been trying really hard to solve the linear PDE

. Where R is a function R(t,q(t),p(t)) and H is the hamiltonian H=   .

(dH/dp= p and dH/dq= -2q-2), q and p depends on the time t, and I'm supposed to solve the PDE and then plot the gaussian distribution (2D).

I tried doing this:

pde := diff(R(t, q1(t), p1(t)), t) = -(diff(R(t, q(t), p(t)), q(t)))*p(t)+(diff(R(t, q(t), p(t)), p(t)))*(-2*q(t)-2)

But pdsolve(pde) gives me:  "Error, (in pdsolve/info) the name of the indeterminate function must be given".

When I change q(t) to q and p(t) to p I get:

R(t, q, p) = _F1(p^2-2*q^2-4*q, -(1/2)*ln(sqrt(2)*q+p+sqrt(2))*sqrt(2)+t)

And then I'm lost. How do I solve this PDE in maple?

Thankful for any help