Please help plot solution of ODE in polar coords or tell how can i define a piecewise function that will make me able to plot the right and left side of singularities.

>sys1:=diff(r(t),t$2)=2*cos(teta(t))/r(t)^3,diff(teta(t),t$2)=sin(teta(t))/r(t)^3;funcs:=[r(t),teta(t)]:InC:=r(0)=1,teta(0)=15,D(r)(0)=0,D(teta)(0)=-2;

>FNUM:=dsolve({sys1,InC},numeric,funcs);

>odeplot(FNUM,funcs,t=0..230,numpoints=2000,coords=polar,view=[-20..20,-20..20]);

Thanks

Hello

I have the following nonlinear differential equation:

deq := (diff(y(x), x, x))*y(x)-1+x*y(x)^2 = cos(x);

I solved it numerically:

sol := dsolve({deq, y(0) = 1, (D(y))(0) = 1}, numeric);

ysol := proc (x) options operator, arrow; rhs(sol(x)[2]) end proc;

plot('ysol(x)', x = 0 .. 5);

but I would like to substitute it to the left side of deq and plot it, to be sure that it's plot is the same as cos(x).

My question is in regards to the events feature in dsolve numeric.

At a particular event time, I was wondering if it is possible to call a previous moment, that is something like

eq:={ diff(y(t),t) = y(t) };

ic:={ y(0) = 2 };

de:=dsolve( eq union ic, numeric, events=[[ t =5, [ y(t) = y( t - 2 ) ]]],range=0..10);


If it is possible to "globaly" declare previous steps of the dsolve, I believe that the above de would work. However,...

Hi everyone, here we are again with more serius issues this time.

I have a system of DE to solve. My system is made of coupled 3 PDE`s with 1 ODE. My problem is that the computation is aborted due failure at memory allocation, here is the message:

"Error, (in factor/nexteval) Cannot Allocate Memory (size=151060480)"

I`ve checked the kernelopts about datalimit and its already infinity. My computer is a Turion x2 with 4Gb of Ram (system...

Hello,

I want to evaluate an integral over the Dirac function with basically the following assignments. (I had some troubles parsing here...) Then I want to plot function rho(epsilon). What I get is just an empty graph with nothing displayed although test has only values in the range -3...3. I am pretty new to maple and don't know how to compute this in another way.

> test(x,y,z) := .2686733768*x^2+.2686733768*z^2-.2178281566+.2686733768*y^2+(-1)*1.000000000*sqrt...

Hello,

I have this relatively simple 4 equations which I am trying to solve simultaneously. But for some reason Maple just returns a pair of empty square brackets as solutions. "[ ]" like this.

I have uploaded the Maple Worksheet for your convenience. It would be very helpful if anyone can take a look at it and point out out the problem. Thank you.

Simultaneous_Eq.mw

I tried to find out whether the expression

g1:=2*mu*(phi+ln(mu/(exp(phi)*sigma2-sigma2+mu)))/((-sigma2+mu)*phi)+mu*(1/(exp(phi)*sigma2-sigma2+mu)-mu/(exp(phi)*sigma2-sigma2+mu)^2)*(exp(phi)*sigma2-sigma2+mu)/((-sigma2+mu)*phi)-mu^2*(phi+ln(mu/(exp(phi)*sigma2-sigma2+mu)))/((-sigma2+mu)^2*phi);

is positive under the given assumptions:

         
is(signum(g1)=1) assuming mu>0, sigma2>0, phi>0, sigma2<>mu;

Having Maple 12 I try to use concurrent gfun version 3.52 and have problems
to run an example (from a lecture):

libname:= "D:\\_Work\\Maple_Work\\z_Packages\\gfun", libname; # my setting

with(gfun) : gfun:-version();
with(NumGfun) :
                                 3.52

Hi

I have a little problem, I tried to find out the Temperature of the Electrons in a Plasma,

the cross section name is sigma and I'm working with noble gases and there Threshold energies.

In the end I wand to find out  T_e but there comes only "Warning, solutions may have been lost"

Can anyone help me please?

Thank you very much

greetings from munich

  restart; interface(version); Digits:=14;

    Classic Worksheet Interface, Maple 12.02, Windows, Dec 10 2008 Build ID 377066

  f:= x -> (x+1)^(x+1);
  simplify(int(f(x),x)): 
  F:=unapply(%,x);
                                        (x + 1)

Hi

I want to solve this

2010.pdf 

Can anyone help me convert this outdated maple code into something current? Particularity I need help finding the equivalent command to "stats:-empirical" as I can't even find documentation for it.

with(stats): with(linalg): with(StringTools):

P1:=matrix([[.6,.3,.1],[.4,.5,.1],[.3,.4,.3]]);

j:=1:  res:="S":

for i to 50 do  

    j:=random[empirical[op(convert(row(P1,j),list))]](): 

I appreciate that maple can solve equations so quickly, but i would like to solve the equation myself and only use the basic features of maple so that I can practice the theory. For example:

for the differential equation y'' + 3y' + 2y = 0 

I would like to assume y = ce^rt then plug it in and get something like

c*(r^2*e^rt + 3r*e^rt + 2e^rt) = 0

maple runs into problems regarding:

-whether the parameters are functions or constants

Different...

Download problemexample.mw

Hello Maple wizards,

After reading the mapleprimes post http://www.mapleprimes.com/posts/36097-Add-Map-And-Seq on the hidden complexities of using thread-safe versions of add (Threads:-Add), I have been struggling to correct a problem similar to the "escaped k" problem described by Joel Riel...