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Error, (in dsolve/numeric/bvp) system is singular ...

Yesterday at 2:29 PM
0 0

g := (y^2-1)^2; I4 := int(g^4, y = -1 .. 1); I5 := 2*(int(g^3*(diff(g, y, y)), y = -1 .. 1)); I6 := int(g^3*(diff(g, y, y, y, y)), y = -1 .. 1); with(Student[Calculus1]); I10 := ApproximateInt(6/(1-f(x)*g)^2, y = -1 .. 1, method = simpson);

dsys3 := {I4*f(x)^2*(diff(f(x), x, x, x, x))+I5*f(x)^2*(diff(f(x), x, x))+I6*f(x)^3 = I10, f(-1) = 0, f(1) = 0, ((D@@1)(f))(-1) = 0, ((D@@1)(f))(1) = 0};

dsol5 := dsolve(dsys3, numeric, output = array([0.]));

Error, (in dsolve/numeric/bvp) system is singular at left endpoint, use midpoint method instead

****************FORMAT TWO ********************************************************

g := (y^2-1)^2; I4 := int(g^4, y = -1 .. 1); I5 := 2*(int(g^3*(diff(g, y, y)), y = -1 .. 1)); I6 := int(g^3*(diff(g, y, y, y, y)), y = -1 .. 1); with(Student[Calculus1]); I10 := ApproximateInt(6/(1-f(x)*g)^2, y = -1 .. 1, method = simpson);
dsys3 := {I4*f(x)^2*(diff(f(x), x, x, x, x))+I5*f(x)^2*(diff(f(x), x, x))+I6*f(x)^3 = I10, f(-1) = 0, f(1) = 0, ((D@@1)(f))(-1) = 0, ((D@@1)(f))(1) = 0};

dsol5 := dsolve(dsys3, method = bvp[midrich], output = array([0.]));
%;
Error, (in dsolve) too many levels of recursion

THANKS A LOT

Error, (in f) unable to store .......................

May 27 2014
0 2

Hello Hello everybody
I have to solve the following differential equation numerically

 > restart:with(plots):
 > mb:=765 : mp:=587 : Ib:=76.3*10^3 : Ip:=7.3*10^3 : l:=0.92 : d:=10: F:=490: omega:=0.43 :
 > eq1:=(mp+mb)*diff(x(t),t\$2)+mp*(d*cos(theta(t))+l*cos(alpha(t)+theta(t)))*diff(theta(t),t\$2)+mp*l*cos(alpha(t)+theta(t))*diff(alpha(t),t\$2)+mp*(d*diff(theta(t),t)^2*sin(theta(t))+l*(diff(theta(t),t)+diff(alpha(t),t))^2*sin(alpha(t)+theta(t)))-F*sin(omega*t)=0;
 (1)
 > eq2:=(mp+mb)*diff(z(t),t\$2)-mp*d*(sin(theta(t)+alpha(t))+sin(theta(t)))*diff(theta(t),t\$2)-mp*l*sin(alpha(t)+theta(t))*diff(alpha(t),t\$2)+mp*(d*diff(theta(t),t)^2*cos(theta(t))+l*(diff(theta(t),t)+diff(alpha(t),t))^2*cos(alpha(t)+theta(t)))+9.81*(mp+mb)-F*sin(omega*t)=0;
 (2)
 > eq3:=mp*(d*cos(theta(t))+l*cos(alpha(t)+theta(t)))*diff(x(t),t\$2)-mp*(l*sin(theta(t)+alpha(t))+d*sin(theta(t)))*diff(z(t),t\$2)+(Ip+Ib+mp*(d^2+l^2)+2*mp*d*l*cos(alpha(t)))*diff(theta(t),t\$2)+[Ip+mp*l^2+mp*d*l*cos(alpha(t))]*diff(alpha(t),t\$2)-mp*sin(alpha(t))*(l*d*diff(alpha(t),t)^2-l*d*(diff(alpha(t),t)+diff(theta(t),t))^2)+mp*9.81*l*sin(alpha(t)+theta(t))+mp*9.81*d*sin(theta(t))=0;
 (3)
 > eq4:=mp*l*cos(alpha(t)+theta(t))*diff(x(t),t\$2)-mp*l*sin(alpha(t)+theta(t))*diff(z(t),t\$2)+(Ip+mp*l^2+mp*d*l*cos(alpha(t)))*diff(theta(t),t\$2)+(Ip+mp*l^2)*diff(alpha(t),t\$2)-mp*9.81*l*sin(alpha(t)+theta(t))+l*d*mp*diff(theta(t),t\$1)^2*sin(alpha(t))=0;
 (4)
 > CI:= x(0)=0,z(0)=0,theta(0)=0,alpha(0)=0,D(x)(0)=0,D(alpha)(0)=0,D(z)(0)=0,D(theta)(0)=0;
 (5)
 > solution:=dsolve([eq1,eq2,eq3,eq4, CI],numeric);
 Error, (in f) unable to store '[0.]/(0.17571268341557e16+[-0.25659510610770e15])' when datatype=float[8]

I don't know why it says : Error, (in f) unable to store '[0.]/(0.17571268341557e16+[-0.25659510610770e15])' when datatype=float[8]

Help pleaase!

thank you !!!

how can I use if when I solve this ode...

March 20 2014
1 12

Dear all;

Please I need your help to find the error in my code.

I want to solve an ode, with condition on step size.

ode := diff(y(x), x) = 2*x+y(x);
f:=(x,y)->2*x-y;

analyticsol := rhs(dsolve({ode, y(0) = 1}));
RKadaptivestepsize := proc (f, a, b, epsilon, N)
local x, y, n, h,k,z,R,p;
p:=2;
h := evalf(b-a)/N; ## we begin with this setpsize
x[0] := a; y[0] := 1; ## Initialisation
for n from 0 to N-1 do  ##loop
x[n+1] := a+(n+1)*h;  ## noeuds
k[1] := f(x[n], y[n]);
k[2] := f(x[n]+h, y[n]+h*k[1]);
k[3] := f(x[n]+h/2, y[n]+h/4*(k[1]+k[2]));
z[n+1] := z[n]+(h/2)*(k[1]+k[2]);## 2-stage runge Kutta.
y[n+1] := y[n]+(h/6)*(k[1]+k[2]+4*k[3]);
R:=abs(y[n+1]-z[n+1]); ## local erreur
hstar:=sqrt(epsilon/R)
if R=<=epsilon    then
x[n] := x[n+1]+h;
y[n]:=y[n+1];
n:=n+1;

else

h:=hstar;
end if
end do;
[seq([x[n], y[n]], n = 0 .. N)];
[seq([x[n], z[n]], n = 0 .. N)];
end proc:

epsilon:=1e-8;

Plot Error of ODE. ...

March 14 2014
0 5

Dear all,

h: stepsize;

x in [0,x0];

I give all the step of my code, but I think there is a mistake. I wait for your Help.

I would like to compute the error between  Method Huen with step size h and step size 2h using the definition of epsilon given below:

## The error written epsilon(x0,h)= sqrt(1/(N+1) * sum_i=0^N  (y_i^{2h}-y_(2i)^h)^2 ), where y_i^(2h) is the approximation of y(i*2*h).

## We want : loglog epsilon versus h.

f:=(x,y)=1/(1+cos(y));

ode:=diff(y(x),x)=f(x,y);

ic:=y(0)=1;  h:=x0/(2*N);

## Method Heun with step size 2h

> Heun1 := proc (f, x0,)

local x, y, i, h, k;

y := Array(0 .. N);

x := Array(0 .. N);

h := evalf((1/2)*x0/N);

x[0] := 0;

y[0] := 1;

for i from 0 to N do

x[i+1] := (2*i+2)*h;

k[1] := f(x[i], y[i]);

k[2] := f(x[i]+h, y[i]+h*k[1]);

y[i+1] := y[i]+h*((1/2)*k[1]+(1/2)*k[2]);

end do;

[seq([x[i], y[i]], i = 0 .. N)];

end proc;

### Now Heun with step size h  ( the same h)

> Heun2 := proc (f, x0,)

local x, y, i, h, k;

y := Array(0 .. N);

x := Array(0 .. N);

h := evalf((1/2)*x0/N);

x[0] := 0;

y[0] := 1;

for i from 0 to N do

x[i+1] := (i+1)*h;

k[1] := f(x[i], y[i]);

k[2] := f(x[i]+h, y[i]+h*k[1]);

y[i+1] := y[i]+h*((1/2)*k[1]+(1/2)*k[2]);

end do;

[seq([x[2*i], y[2*i]], i = 0 .. N)];

end proc;

Problem with Graph...

March 20 2013
0 7

I'm trying to add the output of my function FunctionToTree,which gets all elements from an expression, to a graph using the Graph function but I'm getting erros even when I add it as a list.

with(GraphTheory):
with(SpecialGraphs):
FunctionToTree:=proc(expr)
local elem;
local Tree:=NULL;
local exprType := convert(whattype(expr),string);
local newExpr:=convert(expr,string);
if (nops(expr) <> 1) or (nops(op(1,expr)) <> 1) then
for elem in op(expr) do :

recursive assignment...

March 12 2013
1 2
`part of my codes are:`
`func[1] := (1/2)*(c+s)*x[1]+s*x[3]+(s-c)*x[1]*x[2];func[2] := (1/2)*(c-s)*x[1]+s*x[3]+(s+c)*x[1]*x[2];func[3] := -b*x[2]-x[1]^2; `
`They are just three ODE , how to fix the error?Where is the so-called recursive assignment...?`
`The program works well when:`
`"func[1] := x[2] + (x[1]^2 - x[1]*x[3]);`
`func[2] := - x[1] +  (x[2]^2 + x[1]*x[4]) + x[2]^3;`

weird error that I don't understand...

February 01 2013
0 9

Hi in trying to solve these coupled differential equations i get a weird error:

`> t := diff(X(x), x) = -(1-6*R(x)^(1/2))^(1/2)*x*X(x)/(X(x)*x+R(x))^(1/2), diff(R(x), x) = (1-6*R(x)^(1/2))^(1/2)*x^2*X(x)/(X(x)*x+R(x))^(1/2);                                        (1/2)                                /          (1/2)\                         d           \1 - 6 R(x)     /      x X(x)            --- X(x) = - -----------------------------, `

unable to store HFloat...

November 08 2012
0 7

Hello every one,

I am gettting this error "unable to store HFloat", while solving a system of ODES numerically.

restart:

eq1:=n*(-diff(f(eta),eta\$2))^(n-1)*diff(f(eta),eta\$3)+(2*n/(n+1))*f(eta)*diff(f(eta),eta\$2)

-diff(f(eta),eta\$1)^2-M*diff(f(eta),eta\$1)+M*epsilon+epsilon^2+lambda*f1(eta)=0;

eq2:=diff(f1(eta),eta\$2)+P*(2*n/(n+1))*(f(eta)*diff(f1(eta),eta\$1))=0;

bc:=f(0)=0,D(f)(0)=1,D(f1)(0)=1,D(f)(N)=epsilon,f1(N)=0;

How do i write when too many levels of recursion e...

July 25 2012
0 2

Hi, I'm trying to do this sum in a loop but it says "Error, too many levels of recursion". May I know how should I write it please? Thanks.

for m from 1 to 5 do
Aplus:=Aplus+(m*2):
end do:

I'm trying to get Aplus=(1+(1*2))+(2+(2*2)+....+(5+(5*2))

How do I plot a more than 1000 piece of data as a ...

March 24 2012
0 2

I more than 20000 data points on a an excel file and i want to plot one column against the other. So I imported 10 data points from each column seperately and tried ploting it as a normal plot but it would not work. I kept on getting error messages like

`plot([CosAa,CosBb]);`
```Error, (in plot) incorrect first argument [Array(1..10, 1..1, {(1, 1) = 0.83333e-2,
(2, 1) = 0.166666e-1, (3, 1) = 0.249999e-1, (4, 1) = 0.333332e-1,
(5, 1) = 0.416665e-1, (6, 1...```

Error, (in plots/animate) points cannot be convert...

February 19 2012
0 3
`Does anyone know what the beneath error stated after the following coding means, can't findthe solution,     Although looked in mapleprimes site, and thanks for Joe Riel who pointed out the same problem in 2010,2 June...`
`But, it seems there is still no vivid solution for such problem, how to followk:=20:m:=4:`
`p[0] := 1:`
`tr := 4:`
`frame:=100:omega[n]:=sqrt(k/m):`
`T[n]:=(2 pi/omega[n]):`

June 27 2011
0 3

I was warming by Maple that:

Warning, Exception in unload function 'free': Error, (in _free) invalid dictionary ID

Psuedo Convolution and too many levels of recursio...

November 09 2010
0 1

Why does:

G := Heaviside(x): int(G(x)*G(t-x), x = 0 .. 3);

Produce a "Error, (in unknown) too many levels of recursion"?

I'm puzzling about how to convert differential equ...

September 30 2010
0 2

question.mwWhen I sloving an exercise in my textbook using maple,I had a difficult.

First,I write the differential equation, deq:=[...];then using command,sys1:=DiffEquation(...);I want to get the system transfer function,so I use command tf:=TransferFunction(sys1),but it returns an error[Error, (in DynamicSystems:-TransferFunction) cannot handle input with frequency variable, s].

Then,since TransferFunction...

How do I create multivariable functions?...

September 02 2010
3 1

Hello,

I am just now learning how to use Maple and I am having trouble turning Ohm's Law into a function.

Here is what happens when I try to turn Ohm's Law into a function.

Vrms:=(R,I)->R*I

Error, invalid operator paramet name (and then it puts a dotted red line box around everything to the right of the equal sign)

What really irritates me is that I can type

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