## how to find equation of intersection between a pla...

Hi
i need to find equation of intersection between a plane(Z=0)  and 3d curve like below:

plane :  Z=0

curve:

sqrt(G*(2-G))+(1-G)*(arccos(G-1)+(1/5)*Pi)+k*sqrt(G*(2-G))*cos(sqrt((1+k)/k)*arccos(G-1)+(1/5)*Pi)+sqrt(k/(1+k))*(1-G)*k*sin(sqrt((1+k)/k)*arccos(G-1)+(1/5)*Pi)

I ploted Z=0 plane and that curve . it is like this .
i want equation of the pointed curve(curve equation of intersection between Z=  and curve )in bellow  such as k=f(G) .

best regards

## How can I animate the flattening of an octohedron?...

The worksheet below animates the flattening of a tetrahedron by expanding one of its faces, namely its triangular base.

I would like to animate the flattening of an octahedron so that it assumes the 2D figure resembling the Morley triangle which is included in the worksheet.

Are there documents on the web explaining the technique for doing so? Is there a Maple worksheet available on the web demonstrating the desired animation?

Flatten_a_tetrahedron.mw

## Internal Error in Typesetting invalid object...

Hi, my codes ran smoothly well until I changed some assignment value. It reported invalid object error.

Error, Got internal error in Typesetting:-Parse:-Postprocess : "internal error: invalid object "

Part of the codes are as follows:

""sigma:=0.00002:    m:=5:   n:=4:
Error, Got internal error in Typesetting:-Parse:-Postprocess : "internal error: invalid object "

Could anyone give some hints on what goes wrong here? It seems to be a configuration issue but I completely have no clue..

Best,

Jie

## how do i solve it ?...

with(DEtools);

eq1 := (D(x))(t) = -y(t);

eq2 := (D(y))(t) = x(t)+2*x(t)^3-signum(z(t));

eq3 := (D(z))(t) = w(t);

eq4 := (D(w))(t) = -z(t)*(1+6*x(t)^2);

sys := eq1, eq2, eq3, eq4;

ic1 := [x(0) = 0, y(0) = 0, z(0) = cos(1), w(0) = sin(1)];

ic2 := [x(0) = 0, y(0) = 0, z(0) = cos(2.5), w(0) = sin(2.5)];

ic := ic1, ic2;

DEplot([sys], [x(t), y(t), z(t), w(t)], t = 0 .. 10, [ic], stepsize = 0.5e-1, scene = [x(t), y(t)], linecolor = [blue, red]);

sol1:=dsolve({sys,x(0)=0,y(0)=0,z(0)=cos(1),w(0)=sin(1)},{x(t),y(t),z(t),w(t)},type=numeric);

T := 10.0 ; N := 100 ; h := T/N;

xk := 0;

for k from 1 to N do

solk := sol1(k*h);

xknew := subs(solk,x(t));

yknew := subs(solk,y(t));

if xk*xknew<=0 and abs(yknew-6)<0.5 then break fi;

xk := xknew;

od; sol1(k*h);

temps := proc(alpha,eps)

local sol,solk,T,N,h,k,xk,xknew,yknew,t0,t1,tm,x0,x1,xm;

sol := dsolve({sys,x(0)=0,y(0)=0,z(0)=cos(alpha),w(0)=sin(alpha)},{x(t),y(t),z(t),w(t)},type=numeric);

T := 10.0 ; N := 100 ; h := T/N;

xk := 0;

for k from 1 to N do

solk := sol(k*h);

xknew := subs(solk,x(t));

yknew := subs(solk,y(t));

if xk*xknew<=0 and abs(yknew-6)<0.5 then break fi;

xk := xknew;

od;

t0 := (k-1)*h ; t1 := k*h ;

x0 := subs(sol(t0),x(t)) ; x1 := subs(sol(t1),x(t)) ;

while abs(x0-x1)>eps do

tm := (t0+t1)/2;

xm := subs(sol(tm),x(t));

if xm*x0<0 then x1 := xm; t1:=tm;

else x0 := xm; t0:=tm;

fi;

od;

RETURN(t0);

end;

dicho := proc(eps)

local a,b,m,sola,solb,solm,ta,tb,tm,ya,yb,ym;

a := 1 ; b := 2.5 ;

sola := dsolve({sys,x(0)=0,y(0)=0,z(0)=cos(a),w(0)=sin(a)},{x(t),y(t),z(t),w(t)},type=numeric);

solb := dsolve({sys,x(0)=0,y(0)=0,z(0)=cos(b),w(0)=sin(b)},{x(t),y(t),z(t),w(t)},type=numeric);

ta := temps(a,eps) ; tb := temps(b,eps) ;

ya := subs(sola(ta),y(t)) ; yb := subs(solb(tb),y(t)) ;

while abs(yb-ya)>eps do

m := evalf((a+b)/2);

solm := dsolve({sys,x(0)=0,y(0)=0,z(0)=cos(m),w(0)=sin(m)},{x(t),y(t),z(t),w(t)},type=numeric);

tm := temps(m,eps) ;

yb := subs(sol(tm),y(t));

if (ym-6)*(ya-6)<0 then b := m; yb := ym;

else a := m; ya := ym;

fi;

od;

RETURN(a);

end;

dicho(0.01);

2.136718750

temps(2.136718750,0.01);

8.737500000

DEplot([sys], [x(t), y(t), z(t), w(t)], t = 0 .. 8.7375, [[x(0)=0,y(0)=0,z(0)=cos(2.136718750),w(0)=sin(2.136718750)]], stepsize = 0.5e-1, scene = [x(t), y(t)], linecolor = [blue]);

Error, (in dsolve/numeric/process_input) system must be entered as a set/list of expressions/equations

## homotopy pertubation...

Hi guys,
I am trying write a code for homotopy perturbation, i have already generated the polynomial as you can see, i have also  solve for concentration equation since is not couple. But i have a lot of error massages for temperature, velocity and induced magnetic field. can some one please go through the code?

 >
 > PDEtools[declare](f(x),theta(x),u(x),w(x), prime=x):
 (1)
 >
 >

 > f(x):=sum((p^(i))*f[i](x),i=0..N);
 (2)
 >
 (3)
 >
 >
 (4)
 >
 >
 (5)
 >
 (6)
 >
 (7)
 >
 (8)
 >
 (9)
 >
 (10)
 >
 (11)
 >
 (12)
 >
 >
 (13)
 >
 (14)

 >
 (15)
 >
 >
 (16)

 >
 (17)

 >
 >

## Edge thickness of arcs in DrawGraph...

Hi everyone,

I was wondering how I could modify the thickness of edges in a graph displayed as a Maple plot through DrawGraph. The point is, the graph comprises 100 vertices and 1000 edges. By default, edge thickness is set as 2 but due to the high number of edges I would like to set edge thickness to1 or even 0. How can I do so?

Here is an example with a random graph:

with(GraphTheory) : with(RandomGraphs) : G := RandomGraph(100, 1000) : DrawGraph(G)

Thank you very much

## Is this modification correct?...

This worksheet is a modification to Kitonum's excellent http://www.mapleprimes.com/posts/202222-Contour-Curves-With-Labels.

The mod adds the ability to display labelled contours for expressions in x and y defined parametrically.

Contourplot_with_labels.mw

## How to improve menu speed in Maple 2016...

How to improve menu speed in Maple 2016?

I am using Maple 2016, when I right click the equation, it really takes a long time to show the menu. It seems that the CPU usage and Memory usage is low, it should be fast as it is only a showing menu action, what's wrong with that?

## How can the physics in this worksheet be enhanced?...

The worksheet below rolls an ellipse along the y axis with constant energy.

How can the physics be enhanced to roll the ellipse along a non-linear curve (e.g. a sine curve) with constant energy?

EllipseRoll.mw

## Error, (in ExcelTools:-Export) while processing re...

Help create file Excel in ExcelTools, but error row 564?

thu_file.mw

## How to print data in table format...

Hello

I am looking for the table containing the value m,vv and mm. and these values I can easily copy and paste in excel sheet.

Plz suggest commands

Thanks Dummy_5.mw

## What is the correct syntax for a dsolve numeric di...

The conditional trigger in the code below does not cause a halt although odeplot shows x dipping to a value below 2.

What is the correct coding of this event to cause a halt when x becomes less than 2?

Does any Maple documentation show examples of working discrete events with conditional triggers?

restart;

DE1 := diff(x(t), t, t) = -x(t)-(diff(x(t), t))+y(t);

DE2 := diff(y(t), t, t) = y(t)-(diff(y(t), t))+x(t);

ICs := x(0) = 2, (D(x))(0) = 1, y(0) = 0, (D(y))(0) = 1;

sol1 := dsolve({DE1, DE2, ICs}, {x(t), y(t)}, numeric, event_initial = true, events = [[[0, x(t) < 2], halt]]);

plots:-odeplot(sol1, [t, x(t)], t = 0 .. 3);

## Is the physics correct in this worksheet?...

The animation in this worksheet seems realistic but I wonder if the physics which is implemented is correct since there is no explicit mention of rotational energy.

ThrowBola.mw

## Error, (in unknown) too many levels of recursion...

Hello,

this is my code:

######################

restart;
g(x,y):=min((3+((x-y)^(2))/(10)+(|x+y|)/(sqrt(2))),(-|x-y|+(7)/(sqrt(2))));

q:=0; h(x,y):=Heaviside(g(x,y)-q);

0
(x, y) -> Heaviside(g(x, y))

p := int(int(h(x, y)*exp((-x^2-y^2)*(1/2))/(2*Pi), y = -infinity .. infinity), x = -infinity .. infinity);

Error, (in unknown) too many levels of recursion

######################

I keep having this error message, is this integral impossible to process or is there someting wrong with the code?

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