MaplePrimes - Newest Questions

can not plot numerical ode

Ali Guzel — Fri, 29 May 2026 19:03:07 Z

Can anyone help me?

>	restart: with(plots):

>	h:=0.01: n:=6000: Digits:=18:

>	t[0]:=0: x[0]:=0.2: y[0]:=0.1: epsilon:=20:

>	F:=(x,y)->epsilon(1-x^2)y-x:

>	begin:=time():

>	for k from 0 to n do

>	t[k+1]:=t[k]+h;

>	x[k+1]:=x[k]+h*y[k];

>	y[k+1]:=y[k]+h*F(x[k],y[k]);

>	pt[k]:=[t[k],x[k],y[k]]:

end do:

>	cpu_time:=time()-begin;

>	pointplot3d([seq(pt[j],j=0..n)],axes=normal,symbol=cross,symbolsize=8,color=red,labels=["t","x","y"],orientation=[-90,0]);

>	sys:=diff(X(t),t)=Y(t),diff(Y(t),t)=F(X(t),Y(t));

>	vars:={X(t),Y(t)}: ic:=X(0)=0.2,Y(0)=0.1:

>	sol:=dsolve({sys,ic},vars,numeric,stepsize=h,method=classical[foreuler],output=listprocedure):

>	odeplot(sol,[t,X(t)],0..h*n,axes=normal,style=line,numpoints=n,labels=["t","x"]);

>	XX:=eval(X(t),sol): x1:=XX(1); pt[100];

Download 09-1-1.mws09-1-1.mws09-1-1.mws

Explore, and plot involving fsolve

Hullzie16 — Thu, 28 May 2026 20:20:34 Z

I am trying to plot a function where one of the variables is determind via a procedure that uses fsolve and depends on some parameters. When I go to try and make a plot using Explore to vary the parameters I get the following error:
"in fsolve S is in the equation, and is not solved for"
My worksheet is seen below:

restart;

>	T := 2^(2/3)(16CC(S,mu,Z,Pr)^2Pi^2 + 2Pi^2Z^2 + 16PiSCC(S,mu,Z,Pr) + 3S^2)Pr^(1/3)/(4(4CC(S,mu,Z,Pr)Pi + S)^(2/3)(2Pi^2Z^2 + 4PiSCC(S,mu,Z,Pr) + S^2)^(2/3)CC(S,mu,Z,Pr)^(1/3)*Pi^(2/3))

(1)

>	mu = 2^(2/3)S(16C^2Pi^2 - 2Pi^2Z^2 - S^2)Pr^(1/3)/(4(4CPi + S)^(2/3)(2Pi^2Z^2 + 4CPiS + S^2)^(2/3)C^(4/3)Pi^(2/3))

(2)

>	CC:=proc(S,mu,Z,Pr) fsolve((2),C,C=0.01..100) end proc;

(3)

>	CC(1,0,0.5,0.2)

(4)

>	Explore(plot(T,0..15),parameters=[[mu=0 .. 1,minorticks=0.25],[Z=0..0.5,minorticks=0.1],[Pr=0..1,minorticks=0.25]])

When I try to move the sliders on my parameters this is where I get the error. I want to plot over S, but I can only get CC once I have all the other values including S. I assume it has something to do with the fact that my plotting variable is in the procedure?

Any help would be greatly appreciated, thanks.

Download Explore_Plot_Problem.mw

Why do subs, algsubs, and applyrule fail here?

GFY — Wed, 27 May 2026 09:19:15 Z

I would like to replace in eqn1 the occurrence of

E__b*I__b*Eval(diff(phi__1(x__1), x__1 $ 3), x__1 = L__1)

using the relation defined in bc1.

I have already tried subs, algsubs, and applyrule, but none of them successfully performed the substitution. What would be the recommended or more robust way to carry out this replacement in Maple?
The details are as follows: question527.mw.

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

Saha — Wed, 27 May 2026 08:28:20 Z

Para_1.mw. please help to correct this error.

SMTLIB not found

vv — Tue, 26 May 2026 07:40:28 Z

It seems that in Maple 2025+ on Windows 11, the SMTLIB package is not working. For example:

SMTLIB:-Satisfiable( {x^2+y^2+z^2<1, x*y*z>1} ) assuming real;

complains about error loading external library mplsmtlib.dll.

Is there an explanation, or a workaround?

Using $include to build packages

Anthrazit — Mon, 25 May 2026 11:47:27 Z

I have usually used $include within a module when building packages, where the included file has all the procedures.

What I would like to have is to have the module itself in an external file which would be included.

read "this:///lib/NODEFunctions"; savelib('NODEFunctions', "this://");

$include "NODEXML.mm" # read "this:///lib/NODEXML"; savelib('NODEXML', "this://");

The first 2 lines show the usual way I do it, where NODEFunctions is a module within the Maple file. In that file there is an $include for the proc() parts only.

The second attempt unfortunatly throws a "Error, unexpected string" error. I have tried both with and with a ; at the end of the $include line.

"NODEXML.mm" is a file with the complete module definition with proc().