Advanced Search

nm

11493 Reputation

20 Badges

13 years, 87 days
Contact nm

MaplePrimes Activity


These are questions asked by nm

why expanding PDE makes Maple hangs?...

nm 11493 Maple 2022
expand pde pdsolve
May 04 2022
0 0

To Maple support:

I was investigating this pde from a different forum.

I noticed that when using an expanded version of the pde, Maple hangs. Without expanding the PDE, Maple gives an answer in 2 seconds. 

Why does expanding the PDE makes a difference? I do not have an earlier version of Maple on my new PC to check if this is a new issue or not.
 

> 

interface(version);

`Standard Worksheet Interface, Maple 2022.0, Windows 10, March 8 2022 Build ID 1599809`

> 

Physics:-Version()

`The "Physics Updates" version in the MapleCloud is 1230 and is the same as the version installed in this computer, created 2022, April 21, 9:8 hours Pacific Time.`

> 

restart;
pde1:=VectorCalculus:-Laplacian(u(r,theta),'polar'[r,theta]);
pde1_expanded:=expand(pde1);
bc  := u(1,theta)=sin(theta)^4,u(3,theta)=1;
pdsolve([pde1=0,bc],u(r,theta))
 

(diff(u(r, theta), r)+r*(diff(diff(u(r, theta), r), r))+(diff(diff(u(r, theta), theta), theta))/r)/r

(diff(u(r, theta), r))/r+diff(diff(u(r, theta), r), r)+(diff(diff(u(r, theta), theta), theta))/r^2

u(1, theta) = sin(theta)^4, u(3, theta) = 1

u(r, theta) = (1/52480)*((328*r^6-26568*r^2)*ln(3)*cos(2*theta)+(-r^8+6561)*ln(3)*cos(4*theta)+19680*(ln(3)+(5/3)*ln(r))*r^4)/(ln(3)*r^4)

> 

pdsolve([pde1_expanded=0,bc],u(r,theta)); #HANGS, Waited more than 40 minutes.
> 

 


 

Download hangs_pde.mw

problems with odetest applied to series ...

nm 11493 Maple 2022
ode dsolve differential-equations
May 02 2022
2 2

To Maple support:

I see 2 problems here. Maple solves the ode using series method.

First problem: Using odetest shows the syntax according to help does not work. Which is

           odetest(sol, ODE, series, point = 0);

The above gives internal error.

When changing to the following syntax

         odetest(sol,ODE,type='series',point=0); 

No internal error.

So help page should be corrected.

The second problem is that Maple odetest does not return 0 on its own solution. I verified manually that the solution is correct actually. So I do not know why maple does not return zero here. Simplfication does not help. 
 

> 

interface(version);

`Standard Worksheet Interface, Maple 2022.0, Windows 10, March 8 2022 Build ID 1599809`

> 

restart;
> 

Order:=6;
ode:=x^2*diff(diff(y(x),x),x)+x^2*diff(y(x),x)+y(x) = 0;
maple_sol:=dsolve(ode,y(x),type='series',x=0):
odetest(maple_sol,ode,series,point=0);
odetest(maple_sol,ode,'series',point=0);

6

x^2*(diff(diff(y(x), x), x))+x^2*(diff(y(x), x))+y(x) = 0

Error, (in odetest/series) complex argument to max/min: 13/2-1/2*I*3^(1/2)

Error, (in odetest/series) complex argument to max/min: 13/2-1/2*I*3^(1/2)

> 

odetest(maple_sol,ode,type='series',point=0); #This should return zero, but it does not.

-I*3^(1/2)*x^(3/2-((1/2)*I)*3^(1/2))*(series(-1/2-(I*3^(1/2)/((I*3^(1/2)-1)*(I*3^(1/2)-2)))*x-((1/4)*((5*I)*3^(1/2)+3)/((I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^2-((1/6)*((8*I)*3^(1/2)+9)/((I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^3-((7/16)*((3*I)*3^(1/2)+5)/((I*3^(1/2)-5)*(I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^4+O(x^5),x,5))*_C1+((1/2)*I)*3^(1/2)*x^(3/2+((1/2)*I)*3^(1/2))*(series(1-(1/2)*x+(((1/2)*I)*3^(1/2)/((1+I*3^(1/2))*(I*3^(1/2)+2)))*x^2-((1/12)*((5*I)*3^(1/2)-3)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)))*x^3+((1/24)*(-9+(8*I)*3^(1/2))/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)))*x^4-((7/80)*((3*I)*3^(1/2)-5)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)*(I*3^(1/2)+5)))*x^5+O(x^6),x,6))*_C2+_C1*x^(5/2-((1/2)*I)*3^(1/2))*(series(-I*3^(1/2)/((I*3^(1/2)-1)*(I*3^(1/2)-2))-((1/2)*((5*I)*3^(1/2)+3)/((I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x-((1/2)*((8*I)*3^(1/2)+9)/((I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^2-((7/4)*((3*I)*3^(1/2)+5)/((I*3^(1/2)-5)*(I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^3+O(x^4),x,4))+_C2*x^(5/2+((1/2)*I)*3^(1/2))*(series(I*3^(1/2)/((1+I*3^(1/2))*(I*3^(1/2)+2))-((1/2)*((5*I)*3^(1/2)-3)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)))*x+((1/2)*(-9+(8*I)*3^(1/2))/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)))*x^2-((7/4)*((3*I)*3^(1/2)-5)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)*(I*3^(1/2)+5)))*x^3+O(x^4),x,4))+_C1*x^(3/2-((1/2)*I)*3^(1/2))*(series(-1/2-(I*3^(1/2)/((I*3^(1/2)-1)*(I*3^(1/2)-2)))*x-((1/4)*((5*I)*3^(1/2)+3)/((I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^2-((1/6)*((8*I)*3^(1/2)+9)/((I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^3-((7/16)*((3*I)*3^(1/2)+5)/((I*3^(1/2)-5)*(I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^4+O(x^5),x,5))+_C2*x^(3/2+((1/2)*I)*3^(1/2))*(series(-1/2+(I*3^(1/2)/((1+I*3^(1/2))*(I*3^(1/2)+2)))*x-((1/4)*((5*I)*3^(1/2)-3)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)))*x^2+((1/6)*(-9+(8*I)*3^(1/2))/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)))*x^3-((7/16)*((3*I)*3^(1/2)-5)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)*(I*3^(1/2)+5)))*x^4+O(x^5),x,5))-((1/2)*I)*3^(1/2)*x^(3/2-((1/2)*I)*3^(1/2))*(series(1-(1/2)*x-(((1/2)*I)*3^(1/2)/((I*3^(1/2)-1)*(I*3^(1/2)-2)))*x^2-((1/12)*((5*I)*3^(1/2)+3)/((I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^3-((1/24)*((8*I)*3^(1/2)+9)/((I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^4-((7/80)*((3*I)*3^(1/2)+5)/((I*3^(1/2)-5)*(I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^5+O(x^6),x,6))*_C1+I*3^(1/2)*x^(3/2+((1/2)*I)*3^(1/2))*(series(-1/2+(I*3^(1/2)/((1+I*3^(1/2))*(I*3^(1/2)+2)))*x-((1/4)*((5*I)*3^(1/2)-3)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)))*x^2+((1/6)*(-9+(8*I)*3^(1/2))/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)))*x^3-((7/16)*((3*I)*3^(1/2)-5)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)*(I*3^(1/2)+5)))*x^4+O(x^5),x,5))*_C2+x^(5/2-((1/2)*I)*3^(1/2))*(series(-1/2-(I*3^(1/2)/((I*3^(1/2)-1)*(I*3^(1/2)-2)))*x-((1/4)*((5*I)*3^(1/2)+3)/((I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^2-((1/6)*((8*I)*3^(1/2)+9)/((I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^3-((7/16)*((3*I)*3^(1/2)+5)/((I*3^(1/2)-5)*(I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^4+O(x^5),x,5))*_C1+x^(5/2+((1/2)*I)*3^(1/2))*(series(-1/2+(I*3^(1/2)/((1+I*3^(1/2))*(I*3^(1/2)+2)))*x-((1/4)*((5*I)*3^(1/2)-3)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)))*x^2+((1/6)*(-9+(8*I)*3^(1/2))/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)))*x^3-((7/16)*((3*I)*3^(1/2)-5)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)*(I*3^(1/2)+5)))*x^4+O(x^5),x,5))*_C2+(1/2)*x^(3/2-((1/2)*I)*3^(1/2))*(series(1-(1/2)*x-(((1/2)*I)*3^(1/2)/((I*3^(1/2)-1)*(I*3^(1/2)-2)))*x^2-((1/12)*((5*I)*3^(1/2)+3)/((I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^3-((1/24)*((8*I)*3^(1/2)+9)/((I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^4-((7/80)*((3*I)*3^(1/2)+5)/((I*3^(1/2)-5)*(I*3^(1/2)-4)*(I*3^(1/2)-3)*(I*3^(1/2)-2)*(I*3^(1/2)-1)))*x^5+O(x^6),x,6))*_C1+(1/2)*x^(3/2+((1/2)*I)*3^(1/2))*(series(1-(1/2)*x+(((1/2)*I)*3^(1/2)/((1+I*3^(1/2))*(I*3^(1/2)+2)))*x^2-((1/12)*((5*I)*3^(1/2)-3)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)))*x^3+((1/24)*(-9+(8*I)*3^(1/2))/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)))*x^4-((7/80)*((3*I)*3^(1/2)-5)/((1+I*3^(1/2))*(I*3^(1/2)+2)*(I*3^(1/2)+3)*(I*3^(1/2)+4)*(I*3^(1/2)+5)))*x^5+O(x^6),x,6))*_C2

> 

 


 

Download problems_with_series_solution.mw

 

display problem of constant of integrati...

nm 11493 Maple 2022
alias latex
April 25 2022
1 0

I am using the method of alias(seq(c[k] = _C||k, k = 1..10)); for better latex of constants generated from solving an ode as recommended. See this for example. 

This works well 99.99% of the time. But now I noticed this in Maple 2022. Is this a display issue? When the constant is inside an inert Int it does not display the same as the other constant outside. Also the Latex is not the same. Even though lprint shows they are both correct.

This is the worksheet itself


 

> 

restart;
> 

interface(version);

`Standard Worksheet Interface, Maple 2022.0, Windows 10, March 8 2022 Build ID 1599809`

> 

alias(seq(c[k] = _C||k, k = 1..10));
ode:=x*diff(y(x),x$2)-cos(x)*diff(y(x),x)+sin(x)*y(x)=2;
sol:=dsolve(ode);
lprint(sol)

c[1], c[2], c[3], c[4], c[5], c[6], c[7], c[8], c[9], c[10]

x*(diff(diff(y(x), x), x))-cos(x)*(diff(y(x), x))+sin(x)*y(x) = 2

y(x) = (c[2]+Int((c[1]+2*x)/(exp(Ci(x))*x^2), x))*exp(Ci(x))*x

y(x) = (c[2]+Int((c[1]+2*x)/exp(Ci(x))/x^2,x))*exp(Ci(x))*x

> 

latex(sol)

y \! \left(x \right) =
\left(c_{2}+\textcolor{gray}{\int}\frac{\mathit{c[1]} +2 x}{{\mathrm e}^{\mathrm{Ci}\left(x \right)} x^{2}}\textcolor{gray}{d}x \right) {\mathrm e}^{\mathrm{Ci}\left(x \right)} x

> 

restart;
> 

ode:=x*diff(y(x),x$2)-cos(x)*diff(y(x),x)+sin(x)*y(x)=2;
sol:=dsolve(ode);
lprint(sol)

x*(diff(diff(y(x), x), x))-cos(x)*(diff(y(x), x))+sin(x)*y(x) = 2

y(x) = (_C2+Int((_C1+2*x)/(exp(Ci(x))*x^2), x))*exp(Ci(x))*x

y(x) = (_C2+Int((_C1+2*x)/exp(Ci(x))/x^2,x))*exp(Ci(x))*x

> 

 


 

Download april_25_2022.mw

 

 

First timelimit hang discovered in Maple...

nm 11493 Maple 2022
int timelimit
March 18 2022
0 0

I knew it can't be true that timelimit in Maple 2022 no longer hangs and it is only a matter of time before I find a case where it still hangs.

Here are examples. timelimit hangs. No error or anything, it just hangs. timelimit is just ignored. set the limit to 60 seconds  (CPU time), and waited for 20 minutes (real time) and nothing happend.

I hope in Maple 2023 this will be fixed. Could others confirm this? it only hangs when adding the method=_RETURNVERBOSE otherwise it does not hang.

> 

interface(version);

`Standard Worksheet Interface, Maple 2022.0, Windows 10, March 8 2022 Build ID 1599809`

Examples of timelimit hangs in Maple 2022

 

Example 1

> 

restart;

> 

integrand:=(B*x+A)/(c*x^2+b*x+a)^2/(f*x^2+e*x+d)

> 

try
  timelimit(60,int(integrand,x,method=_RETURNVERBOSE));
catch:
  print("Timed out");
end try;

> 

 

Example 2

> 

restart

> 

integrand:=(5*x^4-x^3+3*x^2+x+2)*(2*x^2-x+3)^(1/2)/(5+2*x)^3

> 

try
    timelimit(60,int(integrand,x,method = _RETURNVERBOSE));
catch:
  print("Timed out");
end try;

> 

 

> 

 

Download int_hangs.mw

Maple 2022 resets to "share one engine a...

nm 11493 Maple 2022
March 18 2022
0 6

This is a serious problem.

I change "how should maple handle the creation of new math engine?" to "Create new engine for each document". Then click on "Apply globally".  This is under Tools->Options->General

After I close Maple and start it again, I found it back to "Share one engine among all documents" ??

Why is that and how to make this permanent? 

Btw, the start Maple 2022 icon still says "Maple 2022 shared server". THis is in the start program menu. I complained about this in Maple 2021 but it is still not fixed.  https://www.mapleprimes.com/questions/231901-Why-Maple-2021-Only-Shows-shared-Server

I do not think this has anything to do with it. But who knows.

I noticed this when I started new worksheet and could not do anything in it because another worksheet was running something even though I made sure I had set the engine to start new one for each worksheet (this is the very first thing I do after I install Maple each time).

Any workaround to make the setting for the engine not change after closing Maple?

Windows 10. Maple 2022.

First 74 75 76 77 78 79 80 Last Page 76 of 202