MaplePrimes - answers and comments on Question, Problems with DEplot

Related to earlier question

Preben Alsholm — Sun, 20 Jan 2013 05:18:16 Z

This seems to be related to

http://www.mapleprimes.com/questions/142322-Why-Has-The-Plot-Command-Deteriorated#comment142326

And indeed, it is the same problem:

restart;
eqn3:=diff(y(x),x)=x+sin(y(x));
IC3:=[y(0)=2];
DEtools[DEplot](eqn3,[y(x)],x=-5..5,IC3,y=-5..5,arrows=none,linecolor=BLACK);
plottools:-getdata(%);
M:=%[-1];
has(M,HFloat(undefined));
interface(rtablesize=infinity);
M;
M1:=M[9..-12,..];
plot(M1);

I hope this won't have to wait for Maple 17!

Added: The following simple remedy works (at least in the present case):

restart;
eqn3:=diff(y(x),x)=x+sin(y(x));
IC3:=[y(0)=2,y(0)=3];
DEtools[DEplot](eqn3,y(x),x=-5..5,IC3,y=-5..5,linecolor=black); p:=%:
eval(p,[undefined,undefined]=NULL);

#A more general version also works for the case in the link:

evalindets(p,Or(Matrix,listlist),m->remove(hastype,convert(m,listlist),undefined));

variable change works for 16.02

Christopher2222 — Thu, 31 Jan 2013 22:33:30 Z

Changing x to some other variable, say t, appears to work in 16.02

with(DEtools):
eqn3 := diff(y(t), t) = t+sin(y(t));
IC3 := [y(0) = 2, y(3) = 0];
DEplot(eqn3, [y(t)], t = -5 .. 5, IC3, y = -5 .. 5, arrows = comet, linecolor = BLACK)

**edit add **

It is a range problem bug. Changing your x range x=-3..2 will remedy the problem and display the solution curves.

eqn3:=diff(y(x),x)=x+sin(y(x));
IC3:=[y(0)=2,y(3)=0];
DEplot(eqn3,[y(x)], x=-3..2 ,IC3,y=-5..5,arrows=comet,linecolor=BLACK);

Plot regression update

cskoog — Thu, 07 Feb 2013 00:30:42 Z

The plotting regression bug may be fixed using the mathdoc.jar update posted here:

http://www.mapleprimes.com/questions/143131-DEPlot-Error-When-Plotting-Solution-Curve?submit=143189#comment143189