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Hi, my dear friend,

i am solving 9 ODE with boundary conditionsNigam.mw

Eq1 := 2.*F1(eta)+diff(H1(eta), eta) = 0

2.*F1(eta)+diff(H1(eta), eta) = 0

(1)

Eq2 := F1(eta)^2-G1(eta)^2+(diff(F1(eta), eta))*H1(eta)-(diff(F1(eta), eta, eta)) = 0

F1(eta)^2-G1(eta)^2+(diff(F1(eta), eta))*H1(eta)-(diff(diff(F1(eta), eta), eta)) = 0

(2)

Eq3 := 2*F1(eta)*G1(eta)+H1(eta)*(diff(G1(eta), eta))-(diff(G1(eta), eta, eta)) = 0

2*F1(eta)*G1(eta)+H1(eta)*(diff(G1(eta), eta))-(diff(diff(G1(eta), eta), eta)) = 0

(3)

Eq4 := 4*F1(eta)*F3(eta)+H3(eta)*(diff(F1(eta), eta))+H1(eta)*(diff(F3(eta), eta))-2*G1(eta)*G3(eta)-2.*F1(eta)^2-1.5*H1(eta)-(diff(F3(eta), eta, eta)) = 0

4*F1(eta)*F3(eta)+H3(eta)*(diff(F1(eta), eta))+H1(eta)*(diff(F3(eta), eta))-2*G1(eta)*G3(eta)-2.*F1(eta)^2-1.5*H1(eta)-(diff(diff(F3(eta), eta), eta)) = 0

(4)

Eq5 := 2*F3(eta)*G1(eta)+4*F1(eta)*G3(eta)+H3(eta)*(diff(G1(eta), eta))-H1(eta)*(diff(G3(eta), eta))-2*F1(eta)*G1(eta)-1.5*H1(eta)*(diff(G1(eta), eta))-(diff(G3(eta), eta, eta)) = 0

2*F3(eta)*G1(eta)+4*F1(eta)*G3(eta)+H3(eta)*(diff(G1(eta), eta))-H1(eta)*(diff(G3(eta), eta))-2*F1(eta)*G1(eta)-1.5*H1(eta)*(diff(G1(eta), eta))-(diff(diff(G3(eta), eta), eta)) = 0

(5)

Eq6 := 4.*F3(eta)+diff(H3(eta), eta) = 0

4.*F3(eta)+diff(H3(eta), eta) = 0

(6)

Eq7 := 6*F1(eta)*F5(eta)-6*F1(eta)*F3(eta)+3.*F3(eta)^2+H1(eta)*(diff(F5(eta), eta))+H3(eta)*(diff(F3(eta), eta))+H5(eta)*(diff(F1(eta), eta))-1.5*(H1(eta)*(diff(F3(eta), eta))+H3(eta)*(diff(F1(eta), eta)))-G3(eta)^2-2*G1(eta)*G5(eta)-(diff(F5(eta), eta, eta)) = 0

6*F1(eta)*F5(eta)-6*F1(eta)*F3(eta)+3.*F3(eta)^2+H1(eta)*(diff(F5(eta), eta))+H3(eta)*(diff(F3(eta), eta))+H5(eta)*(diff(F1(eta), eta))-1.5*H1(eta)*(diff(F3(eta), eta))-1.5*H3(eta)*(diff(F1(eta), eta))-G3(eta)^2-2*G1(eta)*G5(eta)-(diff(diff(F5(eta), eta), eta)) = 0

(7)

Eq8 := 6*G5(eta)*F1(eta)+2*G1(eta)*F5(eta)+4*G3(eta)*F3(eta)-4*F1(eta)*G3(eta)-2*F3(eta)*G1(eta)+H1(eta)*(diff(G5(eta), eta))-1.5*(H1(eta)*(diff(G3(eta), eta))+H3(eta)*(diff(G1(eta), eta)))+H3(eta)*(diff(G3(eta), eta))+H5(eta)*(diff(G1(eta), eta))-(diff(G5(eta), eta, eta)) = 0

6*G5(eta)*F1(eta)+2*G1(eta)*F5(eta)+4*G3(eta)*F3(eta)-4*F1(eta)*G3(eta)-2*F3(eta)*G1(eta)+H1(eta)*(diff(G5(eta), eta))-1.5*H1(eta)*(diff(G3(eta), eta))-1.5*H3(eta)*(diff(G1(eta), eta))+H3(eta)*(diff(G3(eta), eta))+H5(eta)*(diff(G1(eta), eta))-(diff(diff(G5(eta), eta), eta)) = 0

(8)

Eq9 := 6.*F5(eta)+F3(eta)+diff(H5(eta), eta) = 0

6.*F5(eta)+F3(eta)+diff(H5(eta), eta) = 0

(9)

bcs1 := F1(0) = 0, F3(0) = 0, F5(0) = 0

F1(0) = 0, F3(0) = 0, F5(0) = 0

(10)

bcs2 := G1(0) = 1, G3(0) = 0, G5(0) = 0

G1(0) = 1, G3(0) = 0, G5(0) = 0

(11)

bcs3 := H1(0) = 0, H3(0) = 0, H5(0) = 0

H1(0) = 0, H3(0) = 0, H5(0) = 0

(12)

bcs4 := F1(10) = 0, F3(10) = 0, F5(10) = 0

F1(10) = 0, F3(10) = 0, F5(10) = 0

(13)

bcs5 := G1(10) = 0, G3(10) = 0, G5(10) = 0

G1(10) = 0, G3(10) = 0, G5(10) = 0

(14)

R := dsolve(eval({Eq1, Eq2, Eq3, Eq4, Eq5, Eq6, Eq7, Eq8, Eq9, bcs1, bcs2, bcs3, bcs4, bcs5}), [F1(eta), F3(eta), F5(eta), G1(eta), G3(eta), G5(eta), H1(eta), H3(eta), H5(eta)], numeric, output = listprocedure)

Error, (in dsolve/numeric/bvp) initial Newton iteration is not converging

 

``


Maple Worksheet - Error

Failed to load the worksheet 

Download Nigam.mwNigam.mw

then i got this error

Error, (in dsolve/numeric/bvp) initial Newton iteration is not converging

i dont know where i need to change.. could you help me..

Hello everyone.

Please can I meet with Computational or/and Numerical anlysts that have worked or working on the algorihms particularly (Runge Kutta Nystrom, Block multistep methods including hybrid and Block Boundaru Value methods) for the solution of both IVP and BVP.

I will appreciante if I can learn from them and possibly collaborate with them. Thank you in anticipation of your positive response.

Hi guys ,

Actually i dont know how to solve the following complicated differential equations by numerical methods ,

numerical.mw

 

Thank you for your attention to this matter

Imagine we have an ODE system 

odeSys := {diff(x(t),t$2)+diff(x(t),t)+x(t)=f(t),diff(y(t),t$2)+2*diff(y(t),t)+3*y(t)=g(t)};

It is easy to transform this system into a first order form by hand. But for larger systems, the procedure by hand becomes very error prone. Is there an intelligent way to transform a system of n scalar ODEs (order m) into a first order system? I know that the first order form is not unique. It is only important to reduce the system to a system of first order equations.

 

I want to solve the system of differential equations
sys :=
  diff(x(t,s),t) = y(t,s),
  diff(y(t,s),t) + x(t,s) = 0;

subject to the initial condition
ic := x(0,s) = a(s),
      y(0,s) = b(s);

where a(s) and b(s) are given.

This looks like a system of PDEs but actually it is a system
of ODEs because there are no derivatives with respect to s.
It is easy to obtain the solution by hand:

x(t,s) = b(s)*sin(t) + a(s)*cos(t)
y(t,s) = b(s)*cos(t) - a(s)*sin(t)

I don't know how to get this in Maple, either through dsolve()
or pdsolve().

Actually both dsolve({sys}) and pdsolve({sys}) do return
the correct general solution, however dsolve({sys, ic})
or pdsolve({sys, ic}) produce no output.  Is there a trick
to make the latter work?

 

So, I'm trying to delelop an algorithm for the method of multiple scales. Starting with a simple ODE:

diff(x(t), `$`(t, 2))+x(t) = 0

After scaling, it should be written in the form:

(d/dT[0]+epsilon*d/dT[1]+epsilon^2*d/dT[2])^2*(epsilon^3*X[3]+epsilon^2*X[2]+epsilon*X[1])+epsilon*X[1]+epsilon^2*X[2]+epsilon^3*X[3] = 0

A proto-algorithm would be:

restart;
ode := diff(x(t), `$`(t, 2))+x(t) = 0;
i_ini := 1; i_fin := 3; j_ini := 0; j_fin := 2;
PDEtools:-dchange({t = sum(epsilon^j*T[j], j = j_ini .. j_fin), x(t) = sum(epsilon^i*X[i](T[1]), i = i_ini .. i_fin)}, ode, [{T[0], T[1], T[2]}, {X[1], X[2], X[3]}])

It is not working, though. Could anyone help me out?

Thanks in advance.

i want to solve this equation,

y''(x)=5*exp(-10/y'(x)) on ]0,15[ with y(0)=0,y(15)=2 

can any one help me ? thank you

Hi, I'm trying to solve this ode:
restart; with(plots); with(DEtools);

l := t -> 0.5*tanh(0.5*t);

deq := diff(f(t), t)*l(t)*(diff(f(t), t, t)*l(t)+9.8*sin(f(t)))+diff(l(t), t)*(diff(f(t), t)^2*l(t)-9.8*cos(f(t))+4*(l(t)-0.5)) = 0;

sol := dsolve({deq, f(0) = 0, D(f)(0) = 0.1}, f(t), numeric);

 

but getting an error:

Error, (in dsolve/numeric/checksing) ode system has a removable singularity at t=0. Initial data is restricted to {f(t) = 1.77632183122019}
 

How can I possibly fix this?

Respected member!

Please help me in finding the solution of this problem....
 

NULL

 

 

NULL

>   

``

NULL

restart

with(RealDomain):

r := .2:

k := 5;

5

(1)

BCSforNum1 := u(0) = 0, (D(u))(0) = 1+beta*(((D@@2)(u))(0)-(D(u))(0)*RealDomain:-`^`(k, -1)), (D(u))(m) = 0, ((D@@2)(u))(m) = 0;

u(0) = 0, (D(u))(0) = 1+.2*((D@@2)(u))(0)-0.4000000000e-1*(D(u))(0), (D(u))(6) = 0, ((D@@2)(u))(6) = 0

 

v(0) = 1, v(6) = 0

(2)

numsol1 := dsolve({BCSforNum1, BCSforNum2, ODEforNum1, ODEforNum2}, numeric, output = listprocedure)

Error, (in dsolve/numeric/bvp) initial Newton iteration is not converging

 

``


 

Download mplprimes.mw

Dear please check once it showing an error program.mw as intial value is not conververging

Dear sir,

I tried to solve a fourth order problem. But I got the error message as better to use midpoint method. Can I know what is midpoint method and here I uploading the problem please verify it if I did anything mistake?program.mw

i am interested to numerically solve the 3 non-linear coupled ODE's in the 3 different intervals of rho(define in attached file) for the different corresponding parameters alpha and beta at i=0..2.

density_interval_solution.mw 

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.

Dear All,

The following code calculates the Rotation_number for given set of parameters. I would like to plot the value of Rotation_number against R for R from 500 to 1000. Since there are many variables for each iteration, I would like to know if there is a way to create a for loop for the following code while automatically clear variables except for Rotation_number to speed it up? 


 

``

restart:
with(plots): with(DEtools): with(plottools):with(LinearAlgebra):
t_start:=2500: t_end:=5000:

b:=-3: c:=3: v1:=1: f:=-4: v2:=2.0: omega:=1: epsilon:=evalf(1/R): R:=100: k:=0.25:

kH:=(c+1)/(b-1):

sys:=diff(u1(t),t)=v1*u1(t)-(omega+k*u2(t)^2)*u2(t)-(u1(t)^2+u2(t)^2-b*z(t)^2)*u1(t),
     diff(u2(t),t)=(omega+k*u1(t)^2)*u1(t)+v1*u2(t)-(u1(t)^2+u2(t)^2-b*z(t)^2)*u2(t),
     diff(z(t),t)=z(t)*(kH*v1+c*u1(t)^2+c*u2(t)^2+z(t)^2)+epsilon*z(t)*(v2+f*z(t)^4):

solA:=dsolve({sys, u1(0)=0.6, u2(0)=0.6, z(0)=0.1},
             {u1(t),u2(t),z(t)},
              numeric, method=rkf45, maxfun=10^7,
              events=[[[u1(t)=0, u2(t)>0], halt]]):
evs:=Array():
evs(1,1..4):=Array([t,u1(t),u2(t),z(t)]):
interface(warnlevel=0):

for k from 2 do
    w:=solA(t_end):
    if rhs(w[1])<t_end
    then evs(k,1..4):=Array(map(rhs, w));
         solA(eventclear);
    else break;
    fi
od:

interface(warnlevel=3):
M:=DeleteRow(convert(evs,matrix),1):

T:=M[..,1]:

for i from 1 do
tt:=T[i]:
if tt>=t_start then break; end if;
end do:

R:=M[i..,3]: Z:=M[i..,4]:

N_alpha:=numelems(R):

r_center:=add(R[i],i=1..N_alpha)/N_alpha:
z_center:=add(Z[i],i=1..N_alpha)/N_alpha:

Zshift:=Z-~r_center: Rshift:=R-~z_center:

alpha:=(arctan~(Zshift/~Rshift)+(Pi/2)*sign~(Rshift))/~(2*Pi)+~0.5:



alpha2:=alpha[2..N_alpha]:
alpha1:=alpha[1..N_alpha-1]:

del_alpha:=alpha2-alpha1:
m:=numelems(del_alpha):

for i from 1 to m do

if del_alpha[i]<0
then del_alpha[i]:=del_alpha[i]+1;
else del_alpha[i]:=del_alpha[i];
fi:
od:

Rotation:=add(del_alpha[i],i=1..m)/m;

HFloat(0.8000000001553702)

(1)

NULL

Rotation_number.mw

Thank you!

Very kind wishes,

Wang Zhe

TQ.mw

Can any one help for finding the solution of these differntial equations and then plotting the graph for differnt values of M

(FILE ATTACHED)
 

eqn1 := (R/(R-theta(eta))+Omega)*(diff(f(eta), `$`(eta, 3)))+f(eta)*(diff(f(eta), `$`(eta, 2)))+R*(diff(f(eta), `$`(eta, 2)))*(diff(theta(eta), eta))/(R-theta(eta))^2+Omega*(diff(g(eta), eta))+lambda*theta(eta)*Cos(alpha)-M*(diff(f(eta), eta))^2 = 0; eqn2 := (R/(R-theta(eta))+(1/2)*Omega)*(diff(g(eta), `$`(eta, 2)))-2*Omega*(2*g(eta)+diff(f(eta), `$`(eta, 2)))+(diff(f(eta), eta))*g(eta)+(diff(g(eta), eta))*f(eta)+R*(diff(g(eta), eta))*(diff(theta(eta), eta))/(R-theta(eta))^2 = 0; eqn3 := (1+`&epsilon;`*theta(eta))*(diff(theta(eta), `$`(eta, 2)))+`&epsilon;`*(diff(theta(eta), eta))^2+Pr*(f(eta)*(diff(theta(eta), eta))-(diff(f(eta), eta))*theta(eta))+Q*theta(eta)+L*exp(-eta) = 0

(R/(R-theta(eta))+Omega)*(diff(diff(diff(f(eta), eta), eta), eta))+f(eta)*(diff(diff(f(eta), eta), eta))+R*(diff(diff(f(eta), eta), eta))*(diff(theta(eta), eta))/(R-theta(eta))^2+Omega*(diff(g(eta), eta))+lambda*theta(eta)*Cos(alpha)-M*(diff(f(eta), eta))^2 = 0

 

(R/(R-theta(eta))+(1/2)*Omega)*(diff(diff(g(eta), eta), eta))-2*Omega*(2*g(eta)+diff(diff(f(eta), eta), eta))+(diff(f(eta), eta))*g(eta)+(diff(g(eta), eta))*f(eta)+R*(diff(g(eta), eta))*(diff(theta(eta), eta))/(R-theta(eta))^2 = 0

 

(1+epsilon*theta(eta))*(diff(diff(theta(eta), eta), eta))+epsilon*(diff(theta(eta), eta))^2+Pr*(f(eta)*(diff(theta(eta), eta))-(diff(f(eta), eta))*theta(eta))+Q*theta(eta)+L*exp(-eta) = 0

(1)

Omega := 2.; M := .5; R := 5; lambda := 20; `&epsilon;` := .2; Pr := 1; Q := .5; L := .5; W := .5; n := .1; alpha := (1/6)*Pi

bc := f(0) = W, (D(f))(0) = 0, (D(f))(infinity) = 0, (D(theta))(0) = -1, theta(infinity) = 0, g(0) = -n*(DD(f))(0), g(infinity) = 0

f(0) = W, (D(f))(0) = 0, (D(f))(N) = 0, (D(theta))(0) = -1, theta(N) = 0, g(0) = -n*(DD(f))(0), g(N) = 0

(2)

``


 

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