Hi All,

Would anybody be able to explain to me how to find the steady state temperature distribution in maple using the finite difference method?

Any help wouild be greatly appreciated.

Cheers

Joel

Hi

I am getting the following error in Matlab for an equation that I converted from Maple using the Matlab() command.

"Subscript indices must either be real positive integers or logicals."

Maple does show this warning before giving the Matlab code.

"Warning, the function names {alphaD} are not recognized in the target language"

The equation is the derivative of a function with more than one variable.

Please help to sort this out.

Thanks

Hi,

I have some data (points of results -> a list of x - data and a list of corresponding y - data) and I would like to fit a curve to this data.  curves does not fit very well to the data points.

Can anybody give me a method to fit a curve to the data?

Tanks!

The data are:

I get "hypergeom" with Thomas Calculus exercise 5.6.15 for some unknown reason. the other exercises don't get this. See it at:

http://i36.tinypic.com/258lzqx.jpg

how can i get rid of the "hypergeom" in the answer ?

Hello!

I have just found this incorrect behaviour of is  (Maple 12):

restart;

Hi all,

> deq := diff(x(t), t) = 3*x(t)/t+(9/2)*t-13;

                             d         3 x(t)   9       
                     deq := --- x(t) = ------ + - t - 13
                             dt          t      2       
> ci := x(3) = 6;

                               ci := x(3) = 6
> p := dsolve({ci, deq}, x(t), numeric);

                        p := proc(x_rkf45)  ...  end;
> plots[odeplot](p, view = [-1 .. 4, -10 .. 10]);

> p(0);

                  [                                     -8]
                  [t = 0., x(t) = 8.65023735199754930 10  ]

but if I do:

> q := dsolve({ci, deq}, x(t), type = numeric, method = taylorseries);

                    q := proc(x_taylorseries)  ...  end;
> plots[odeplot](q, view = [-1 .. 4, -10 .. 10]);


> q(0);

                             [t = 0., x(t) = 0.]
> solex := rhs(dsolve({ci, deq}, x(t)));

                                    9  2   13      3
                         solex := - - t  + -- t + t 
                                    2      2        

But in cases where I don't know the answer, which should I trust?  here is another one

> deq := diff(x(t), t) = 1-t-x(t)/t;

                               d                 x(t)
                       deq := --- x(t) = 1 - t - ----
                               dt                 t  
> ci := x(1) = 0;

                               ci := x(1) = 0
> q := dsolve({ci, deq}, x(t), numeric);

                        q := proc(x_rkf45)  ...  end;
> q(0);

                    [t = 0., x(t) = 1.73003351210698475]
> plots[odeplot](q);


> solex := rhs(dsolve({ci, deq}, x(t)));

                                    1  2   1      1 
                         solex := - - t  + - t - ---
                                    3      2     6 t
> plot(solex, t = -1 .. 1, -100 .. 100);


and for the finish

> r := dsolve({ci, deq}, x(t), numeric, method = taylorseries);

                    r := proc(x_taylorseries)  ...  end;
> plots[odeplot](r);
%;
Warning, could not obtain numerical solution at all points, plot may be incomplete

> r(0);

Error, (in r) cannot continue integration past t=0.585794295977905e-4, step size dropped below minimum

Thanks in advance for any help

Mario

Hi all,

Hi

Just started using the global optimization toolbox. Not sure if I am doing something wrong or if it is genuinely awful. After about 20mins it produces a fit that is dreadful,an alternative cheaper package (scop) produces a great fit in about 2 mins. Can anyone see what I'm doing wrong?

Hi

Just started using the global optimization toolbox. Not sure if I am doing something wrong or if it is genuinely awful. After about 20mins it produces a fit that is dreadful,an alternative cheaper package (scop) produces a great fit in about 2 mins. Can anyone see what I'm doing wrong?

I have the following nonlinear ODE symmetric in the functions A(r) < - > B(r):

eq:= diff(A(r),r)^2/A(r)^2 + diff(A(r),r)*diff(B(r),r)/A(r)/B(r) + diff(B(r),r)^2/B(r)=k;

The task is to solve for A(r) in terms of B(r) and it goes like this: solve the quadratic equation for A'/A in terms of B'/B (or vise versa cause equation is symmetric) and then integrate.

dsolve(eq, A(r));  produces the required solution for A(r) in terms of integral over B and B'.

dsolve(eq, B(r)); returns nothing.

Should it really take 103 seconds to build a list of 95850 floats on a 2GHz machine?

I am using the data from the attached .m file and using the following code (I am not doing anything here but I will be) on the list, angles1_s which is read in from the .m file

Hello,

I need to plot a solid circle on a line. The problem is that you can see the line through the circle:

with(plots):
with(plottools): 
l := plot(x,color=red,thickness=3): 
d:=disk([0.5, 0.5],0.05,color=black): 
display({l, d},view=[0..1,0..1]);

I think I need something which is called in Microsoft Office products "Bring Forward (or to Front)" and "Send Backward (to Back)"

I suppose it's something very simple but I just cannot find it!

Thank you!

I have this function:

Eig1 := proc (R) options operator, arrow; (1/9*(-27*deltaE^3*R^9-10*M^6+3*sqrt(-189*deltaE^4*R^12*M^4-147*deltaE^2*R^6*M^8-27*M^12+60*deltaE^3*R^9*M^6))^(1/3)-(-deltaE^2*R^6-7/9*M^4)/(-27*deltaE^3*R^9-10*M^6+3*sqrt(-189*deltaE^4*R^12*M^4-147*deltaE^2*R^6*M^8-27*M^12+60*deltaE^3*R^9*M^6))^(1/3)+2/3*deltaE*R^3+2/9*M^2)/R^3 end proc

where:

> deltaE := 0.355 , and

M := sqrt(540000.0000)