My problem is the following:

deq1:=2*[(y(x)*(diff(y(x), x, x))-1)/sqrt(1+(diff(y(x), x))^2)+(diff(y(x), x, x))/(1+(diff(y(x), x))^2)] = cos(x);
I do this way (error anyway):
deq := (y(x)*(diff(y(x), x, x))-1)*(1+(diff(y(x), x))^2)+(diff(y(x), x, x))*sqrt(1+(diff(y(x), x))^2)-cos(x)*sqrt(1+(diff(y(x), x))^2)*(1+(diff(y(x), x))^2) = 0
sol := dsolve([deq, y(0) = 0, (D(y))(0) = 0], y(x), numeric, range = 0 .. 3)

So, my question is, how can I determine the integral of the left side of deq1? ...

Hello,

I have this differential equation:

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

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

After that I have a numerical solution for y, and for diff(y(x),x). But I would like to plot diff(y(x),x,x). (and then diff(y(x),x,x)+diff(y(x),x)*cos(x)). How can I do that?

Any help will be appreciated,

L

Hello there,  How can I compile this? I used   boundarycompiled := Compiler:-Compile(findboundary)    but this didnt work. Thanks in advance

> findboundary:=proc(a,b,c,d,e,f,g,h)  ;
> global A,B,lowerbound,upperbound;
> A, B := solve(a = b, x), solve(c = b, x);
> x1a, x1b := evalf(solve((x-e)^2+(a-f)^2-g^2)); if x1a < x1b then minx1, maxx1 := x1a, x1b else minx1, maxx1 := x1b, x1a end if;
> x2a, x2b := evalf(solve((x-e...

Hi. I have to solve the following differential equation numerically

f := [(diff(y(x), x))*(diff(y(x), x, x))/sqrt(y(x)^2+diff(y(x), x))+diff(y(x), x, x)] = x^6

dsolve({f, y(0) = 2, (D(y))(0) = 1.5, (D(D(y)))(0) = 1}, y(x), numeric, range = 0 .. 10)

Error, (in DEtools/convertsys) unable to convert to an explicit first-order system

I don't know what to do, I've read help and work on this for 3 days now.

There exists a broken link on the last post here http://www.mapleprimes.com/posts/41183-Tip-Transpose-A-Pair-Of-Indices-Of-An-Array?r=76538 

Hi

I guess I should know this but what is the difference between a Matrix and an Array in Maple?

thanks

I've been given the relationship:

R*sqrt(sigma)-1-(1)/(4)*(l-(2*kappa*R^2)/(R*sqrt(sigma)))/(1+coth(R*sqrt(sigma)))-kappa*R^2/6+m/(2*R), for the particular case where m=l=0, and where

R=exp[(kappa*(R^2))/6]. On a sketch of R vs kappa, apparently sigma >0 on the lower branch, but there should be some sigma < 0 on the upper branch.

To attempt to solve this whole problem, I use the following commands:

restart;with(plots):

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