How do I solve a set of differential equations in ...

Hi, my dear friend,

i am solving 9 ODE with boundary conditionsNigam.mw

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Maple Worksheet - Error

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..

Evaluating a list of equations...

Greetings,

i have a problem working with a list of equations. The background for the whole thing is simulating the movement of 4 astronomical bodies with Newtons equation. Currently i have a list which looks like this (read x(1,1) as x-coordinate body 1 time =1):

[ x(1,1)=1,12312,y(1,1)=2,3123,z(1,1)=4,141,...,x(1,n)=5,0102,y(1,n)=0,912,z(1,n)=8,1232,...,x(4,n)=5,92y(4,n)=1,656,z(4,n)=3,141]

so i basically have all the information about where the bodies are.

I want to use this information to create a 3D-pointplot. I know that the point plot requires a special input form ( {[x(1,1),y(1,1),z(1,1],[x(1,2),y(1,2),z(1,2)].....} ), but i alread have managed to convert my original list accordingly. However, i cannot use this new list for pointplot because it contains equations and not simple values.

So how do i get from a list as shown above to a list which contains merely the numeric values?

Trying to use Newton's Method within a tolerance, ...

Basically what I'm trying to do is use Newton's method to find the root of f(x)=sqrt(x)+ln(0.1x) starting at x0=5 within a tolerance of 0.001.

f := proc (x) options operator, arrow; sqrt(x)+ln(.1*x) end proc

> xk := 1.0;
print(`output redirected...`); # input placeholder
1.0
> for k to 6 do xk1 := xk-f(xk)/(D(f))(xk); xk := xk1 end do;

When I do that, Maple barfs out pages of nonsense when I'm looking for it to give numerical values. It seemed to work fine with a different function, so maybe that's part of the problem? But I need to do it with the function I asked about.

convergence of newton method...

how i can find order of convergence of newton method by expanding taylor series?? plz send me code???

Newton iteration is not converging...

Dear All,

I am going to solve the following systems of ODEs but get the error: Newton iteration is not converging.
Could you please share your idea with me. In the case of AA=-0.2,0,0.2,0.4,...; I could get the solution.

restart;
with(plots);
Pr := 2; Le := 2; nn := 2; Nb := .1; Nt := .1; QQ := .1; SS := .1; BB := .1; CC := .1; Ec := .1; MM := .2;AA:=-0.4;

Eq1 := diff(f(eta), `\$`(eta, 3))+f(eta).(diff(f(eta), `\$`(eta, 2)))-2.*nn/(nn+1).((diff(f(eta), eta))^2)-MM.(diff(f(eta), eta)) = 0; Eq2 := 1/Pr.(diff(theta(eta), `\$`(eta, 2)))+f(eta).(diff(theta(eta), eta))-4.*nn/(nn+1).(diff(f(eta), eta)).theta(eta)+Nb.(diff(theta(eta), eta)).(diff(h(eta), eta))+Nt.((diff(theta(eta), eta))^2)+Ec.((diff(f(eta), `\$`(eta, 2)))^2)-QQ.theta(eta) = 0;
Eq3 := diff(h(eta), `\$`(eta, 2))+Le.f(eta).(diff(h(eta), eta))+Nt/Nb.(diff(theta(eta), `\$`(eta, 2))) = 0;

bcs := f(0) = SS, (D(f))(0) = 1+AA.((D@@2)(f))(0), theta(0) = 1+BB.(D(theta))(0), phi(0) = 1+CC.(D(phi))(0), (D(f))(etainf) = 0, theta(etainf) = 0, phi(etainf) = 0

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

Convergence of Newton method...

let γ be the root

i have to apply taylor series on f(x) and then do some substitution like (helped by a member of Mapleprime)

restart;
taylor(f(x), x = gamma, 8);
f(x[n]) := subs([x-gamma = e[n], f(gamma) = 0, seq(((D@@k)(f))(gamma) = factorial(k)*c[k]*(D(f))(gamma), k = 1 .. 1000)], %)

then find the derivative of result from above output

i do

b := diff((x[n]), e[n])

basically i have to find the value of newton method which is

yn=xn-f(xn)/D(f)(xn)

here we substitute xn=γ and D(f)(xn)=b

and then want to apply f on yn

there are to problem which i face

1  f(xn)/D(f)(xn) is not in simplified form i-e O(e[n]^8) and O(e[n]^7) is appeared in numerator and denominator respectively. how we get the simplified result.

2 wht step should i do to find f(yn)

plx help me to do this

Is there a way to put in an initial guess for mult...

I would like to use Newton's Method (the multivariate one) in order to solve a system of equations. From what I understand, fsolve is essentially MAPLE's version of the multivariate Newton's Method. Is there a way to do the multivariate Newton's method any other way, other than fsolve? Also, is there a way to specify our own initial guess and tolerance for the Newton's Method and to get other details such as the number of iterations?

methods for solving systems of nonlinear equations...

Hi all!

I do a small calculation and get a system of 6
nonlinear equations.
And "n" is the degree of the equation is float.

Here are the calculations that lead to the system.

restart;
with(DirectSearch):
B:=1:
q:=1:
l:=1:
n:=4.7:
V:=0.05:
N:=1200:

kappa:=Vector(N+1,[]):
theta:=Vector(N+1,[]):
u:=Vector(N,[]):
M:=Vector(N,[]):
Z:=Vector(N,[]):

M_F:=q*(6*l*(z-l)-z^2/2):
M_1:=piecewise((z<l), l-z, 0):
M_2:=piecewise((z<2*l), 2*l-z, 0):
M_3:=piecewise((z<3*l), 3*l-z, 0):
M_4:=piecewise((z<4*l), 4*l-z, 0):
M_5:=piecewise((z<5*l), 5*l-z, 0):
M_6:=6*l-z:
M_finish:=(X_1,X_2,X_3,X_4,X_5,X_6,z)->M_1*X_1+M_2*X_2+M_3*X_3+M_4*X_4+M_5*X_5+M_6*X_6+M_F:

kappa_old:=0:
theta_old:=0:
u_old:=0:
M_old:=0:

step:=6*l/N:
u[1]:=0:
kappa[1]:=0:
theta[1]:=0:

for i from 2 to N do

z:=i*step:
kappa_new:=kappa_old+B/V*(M_finish(X_1,X_2,X_3,X_4,X_5,X_6,z))^n*step:

theta_new:=theta_old+1/2*(kappa_old+kappa_new)*step:

u_new:=u_old+1/2*(theta_old+theta_new)*step:

Z[i]:=z:
kappa[i]:=kappa_new:
theta[i]:=theta_new:
u[i]:=u_new:
kappa_old:=kappa_new:
theta_old:=theta_new:
u_old:=u_new:

end do:

So,my system:

u[N/6]=0;
u[N/3]=0;
u[N/2]=0;
u[2*N/3]=0;
u[5*N/6]=0;
u[N]=0;

I wanted to use Newton's method, but I don't know the initial values X_1..X_6.

Tried to set the values X_1..X_6 and to minimize the functional
Fl:=(X_1,X_2,X_3,X_4,X_5,X_6)->(u[N/6])^2+(u[N/3])^2+(u[N/2])^2+(u[2*N/3])^2+(u[5*N/6])^2+(u[N])^2:

with the help with(DirectSearch):
GlobalOptima(Fl);
But I don't know what to do next

Please, advise me how to solve the system! I would be grateful for examples!

Plotting Newton's Method In Maple...

Hi, I am using Maple 18 and struggling with plotting Newton's Method.

I am wanting use the function f(x)=x^3 +cx + 1 where c is a parameter and uses 100 parameter values between -2 and 0, with 100 iterations of each parameter.

Any help would be brilliant.

Neil

Newtons Method in an Interval...

Hello, I'd like to use Maple to use Newton's Method in an interval to find multiple roots of 4xcos(3x)+(x-2)^2-2=0. What I have so far is:

with(Student[NumericalAnalysis]):
f := 4*x*cos(3*x)+(x-2)^2-2:
Newton(f,x=2,tolerance=10^(-4));

Other than trying out different initial guesses is there a way to do this?

Help with an error in procNewton...

Hello,

Can anyone help me with this error in Maple while using prcNewton to find local extrema:

` `
`> prcNewton := proc () `
`local ftn, strpt, epsilon, maxlps, i, xn, dftn; `
`if 4 < nargs then `
`elif nargs < 2 then end if; `
`if nargs = 2 then `
`epsilon := 1/10000000; `
`maxlps := 1000 `
`elif nargs = 3 then `

Use Newton's Method to Find Local Extrema...

Use Newton's Method to find a local extrema for f(x)=sin(x^2)+x

with start point x=(1,0)

take derivative of f(x) then apply Newton's Method

My teacher started us off with this but I can't seem to get it to work the way she did, any help would be appreciated!

prcNewton:=proc( )

local ftn,strpt,epsilon,maxlps,i,xn,dftn;

if nargs>4 then

Help with Solving this,...

Use Newton’s Method to approximate the indicated root of the equation to correct six decimal places.

The root of 2.2x5 – 4.4x3 + 1.3x2-0.9x-4.0=0 in the interval [-2, -1].

The rest of the assignment states : "

`Start by plotting the function inMaple to get a reasonably good initial approximation. You may use a“while” loop, but do not use existing Maple commands for Newton’s`
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