HI

I am using a simple piece of code to generate Lie derivatives, and I am interested in adapting it so that I can use it with vector Fields where that include RootOf expressions. 

LieDer_with_rootof.mw

The above includes an example where it works, and an example where RootOf appears in the vector field and it does not work. 

i want solve error of PDE2

Download Error10%.mw

Error10%.mw

er.xls

Download import.mw

Exel.xls

my"+cy'+ky=F(t)      y(0)=y_0    and y'(0) =y'_0    (1)

Where F(t) is an external force, m, c and k are positive constants, y is a function of t and cy' is the damping term. Use equation (1) for your topic and F(t) = 0.

Task 2 : Assume that m = 1 unit in equation (1). For each of the following cases (all with m = 1), perform 5 steps of the modified Euler method applied to the coupled first order system you obtained in part (i), taking the step size h = 0.02 and working to 5 decimal places at each stage :

c = 0,  k = 4  , y(0)=1   and y'(0) =0;

c = 2,  k = 0,   y(0)=1   and y'(0) =0;

c = 2,  k = 1,   y(0)=1   and y'(0) =0;

c = 4, k = 6.25,  y(0)=1   and y'(0) =0.

Summarise your step-by-step results for each example in a table like the blank template below.

This is a question based on rewriting the equation as a pair of coupled(simultaneous) first order ODEs of the general form.

If anyone could please help to proceed with this question, as I am not quiet sure how to approach this differential equation. I will really appreciate your help please.

Thank you

I am solving some system of linear equations using fsolve(), I will like to obtain my answers without the attached label, i.e. instead of saying {x=2, y = 3} I need my result to be {2,3} because I need reuse the result. Please, help. Thanks.

I seem to be getting false solutions with Maple 2019.2 from solve and cannot figure out why.

Example :

Thus the second reported solution is not a solution after all.

Any ideas are most welcome.

when calculating the exponential integral in maple. Help me please!

Let Q be a quadrilateral which has a inscribed circle and a circumscribed circle. Show that the centers of these 2 circles and the point of intersection of the diagonals
of the quadrilateral are aligned.

restart; unprotect(D, O);

with(plots); with(LinearAlgebra);
Soit Q un quadrilatère qui possède un cercle inscrit et un cercle circonscrit. Montrer que les centres de ces 2 cercles et le point d'intersection des diagonales
du quadrilatère sont alignés.
_EnvHorizontalName := 'x';

_EnvVerticalName := 'y';

Vdot := proc (U, V) add(U[i]*V[i], i = 1 .. 2) end proc;
dist := proc (M, N) sqrt(Vdot(expand(M-N), expand(M-N))) end proc;
EQ := proc (M, N) local eq; eq := (y-M[2])/(x-M[1]) = (N[2]-M[2])/(N[1]-M[1]) end proc;
Pour un quadrilatère A'B'C'D' circonscrit autour d'un cercle avec points de contact A, B, C, D, les droites A'C', B'D', AC, BD sont concourantes
varphi1 := (1/3)*Pi; varphi2 := varphi1+(1/4)*Pi+.1; varphi3 := varphi2+3*Pi*(1/5); varphi4 := 2*Pi-varphi1-varphi2-varphi3; R := 5;
                    varphi4 := -0.514159263
O := [0, 0];
for i to 4 do M || i := [R*cos(varphi || i), R*sin(varphi || i)]; OM || i := plot([O, M || i], color = blue, linestyle = 3); cfOM || i := -1/(diff(solve(EQ(O, M || i), y), x)); eq || i := y = cfOM || i*x+R*sin(varphi || i)-cfOM || i*R*cos(varphi || i); T || i := plot(cfOM || i*x+R*sin(varphi || i)-cfOM || i*R*cos(varphi || i), x = -10 .. 10, color = green) end do;

for i to 4 do j := `mod`(i+1, 4); if j = 0 then j := 4 end if; sol || i := evalf(op(solve([eq || i, eq || j], [x, y]))); P || i := [subs(sol || i, x), subs(sol || i, y)] end do;
for i to 4 do Q || i := geometry:-point(Q || i, P || i[1], P || i[2]) end do;
geometry:-AreConcyclic(Q1, Q2, Q3, Q4, 'cond');
                             false
AC := plot([M1, M3], color = blue);
BD := plot([M2, M4], color = blue);
diago1 := plot([P1, P3], color = coral); diago2 := plot([P2, P4], color = coral);
quadri := plot([seq(M || i, i = 1 .. 4), M1], color = black);
cer := plot([R*cos(t), R*sin(t), t = 0 .. 2*Pi], color = blue);
Points1 := pointplot([seq(M || i[], i = 1 .. 4)], symbol = solidcircle, color = [blue], symbolsize = 15);
Points2 := pointplot([seq(P || i[], i = 1 .. 4)], symbol = solidcircle, color = [green], symbolsize = 15);
Tt1 := plots:-textplot([[M1[], "A"], [M2[], "B"], [M3[], "C"], [M4[], "D"]], font = [times, 10], align = {below, right});
Tt2 := plots:-textplot([[P1[], "A'"], [P2[], "B'"], [P3[], "C'"], [P4[], "D'"], [O[], "O"]], font = [times, 15], align = {above, right});
display([cer, quadri, seq(OM || i, i = 1 .. 4), seq(T || i, i = 1 .. 4), AC, BD, diago1, diago2, Points1, Points2, Tt1, Tt2], axes = none, view = [-9 .. 7, -12 .. 6], scaling = constrained, size = [500, 500]);

I was trying this in Maple to check Mathematica's result, and got this error. But googling and the link Maple gives lead to nothing.

Any one knows why Maple gives this error message here?

restart;

phi:=Pi;
A := <
          <0, 0, exp(I*k1) + m1, exp(I*k2) + m2>|
          <0, 0, exp(I*phi)*(exp(-I*k2) + m2), exp(-I*k1) + m1>|
          <exp(-I*k1) + m1, exp(-I*phi)*(m2 + exp(I*k2)), 0, 0>|
          <exp(-I*k2) + m2, exp(I*k1) + m1, 0, 0>
     >:
LinearAlgebra:-Eigenvectors(A)

Error, (in LinearAlgebra:-Eigenvectors) multiplicity mismatch

fyi, Mathemtica's result is

ClearAll[k1, m1, m2, k2];
Phi = Pi;
H = {{0, 0, Exp[I k1] + m1, Exp[I k2] + m2}, {0, 0, 
    Exp[I Phi] (Exp[-I k2] + m2), Exp[-I k1] + m1}, {Exp[-I k1] + m1, 
    Exp[-I Phi] (m2 + Exp[I k2]), 0, 0}, {Exp[-I k2] + m2, 
    Exp[I k1] + m1, 0, 0}};
Eigenvectors[H]

I tried tracing in Maple, but so far no useful result:

infolevel[all]:=5;
LinearAlgebra:-Eigenvectors(A)

.
.
.
simplify/size: [1/(2+m1^2+m2^2+2*m1*((1/2)*exp(I*k1)+(1/2)*exp(-I*k1))+2*m2*((1/2)*exp(I*k2)+(1/2)*exp(-I*k2)))^(1/2) exp(-I*k1) exp(-I*k2) exp(I*k1) exp(I*k2) _t[1] _t[2] m1 m2 k1 k2]
simplify/size: [exp(-I*k1) exp(-I*k2) exp(I*k1) exp(I*k2) m1 m2 _t[1] _t[2] k1 k2]
simplify/size: [1/(2+m1^2+m2^2+2*m1*cos(k1)+2*m2*cos(k2))^(1/2) exp(-I*k1) exp(-I*k2) cos(k1) cos(k2) _t[1] _t[2] m1 m2 k1 k2]
simplify/do: applying  commonpow  function to expression
simplify/do: applying  power  function to expression
simplify/do: applying simplify/size function to expression

Error, (in LinearAlgebra:-Eigenvectors) multiplicity mismatch

Maple 2019.2.1 on windows

Could anyone help me with the following task?

The simplest case is, for example, 

    If y=y(x). Denote y'(x)=D_x(y). Then we make a change of veriables :

    x=φ(z,w), y=ψ(z,w), where z independent and w=w(z),

    Now the ODE: y'(x)=1 turns to:

    D_z(y)/D_z(x)=1,  i.e. ψ_z+w'(z)ψ_w=φ_z+w'(z)φ_w.

    So we have the relation: D_z=(φ_z+w'(z)φ_w)D_x.

    The task is how to define the operators (D_x, D_z) to transform more complecated ODE of (x,y) (e.g. (D_x+F(x,y))⁵(y)=0,   

     F arbitrary) to its counterpart of (z,w)?

Thank you in advance!

so I can get inert operations but what about parenthesis and built ins?

add(k,k=1..5)

I can't remember the specific code but what I was getting was something like

1 + 3 + 4 + 5 + 6 /4

rather than (1 + 3 + 4 + 5 + 6)/4

and the parenthesis was not showing up and I couldn't use things like add or mul in an inert like form(I think I had to write a loop).

What I had to do was multiply by 1 inertly and then it added the parenthesis.

If I could add inert parenthesis it would have solved the problem and also get built in functions to be inert but only on their ineternal operations.

Help me to solve this problem with pdsolve

Hi
i have N+1 equation like following

i want to solve them. how can i do it?

i think i should first convert them to sequense and then use fsolve code ,but my code will get error!! could you help me?

thanks

Hi,

I'm trying to plot:

I keep getting a what looks like a straight line. it should be a curved line.

I got it to work on :

y = x(x^4 - 10*x^2 + 39)/30

https://www.mathway.com/Algebra

Hi,

I'm wanting to use nonlinear least squares fittting to minimise the error between two curves.

One curve, f₁ , I know the parameters for and the other, f2 , I do not, which is what I am wanting to find through this methood.

f₁=(2*x)/(3+5*x)  

f₂=a₁*(2-exp(-a₂*x)) 

Any help would be muchly appricated, thank you in advance!