The help page for  PDEtools,dsubs  says  "dsubs will substitute the left hand side of each substitution equation until this derivative is eliminated from the target"

Trying a subs like u'=u into the expression u'' gives u -- as it should:

PDEtools:-dsubs(diff(u(x),x) = u(x), diff(u(x),x,x));
                                    u(x)

I would like to use Maple to provide an independent check on a finite element model solution (ANSYS) of a thermal transient analysis of a reinforced concrete shell.  The following information is known about the shell:

Just a simple issue,

When I'm typing in an equation with a lot of brackets, maple automatically underlines the bracket set however if you are at the bottom of the screen the underline will not be visible.  This is just more of an annoyance than a problem.

Perhaps in an update maple could scroll the text up half of a space or so from the bottom of the screen?  or be able to at least scroll the data up the screen.

I'm trying to install Maple 11 in a 64 bit Archlinux system.  The licensing software is only 32 bit, even though Maple itself is 64 bit.  All I needed to do to get around that is install 32 bit glibc libraries (pacman -S lib32-glibc for any Arch users)

How can Maple arrive at the following, for an unspecified function f(x,y), without knowing sufficient conditions (eg. whether the 2nd partials are continuous)?

> # From the ?diff help-page
> diff(f(x,y),x,y) - diff(f(x,y),y,x);
                                      0

Continuity of integrands isn't generally assumed by int (there's a separate optional parameter which enables it...

Hi there,

I'm struggling to understand the dynamics of a 3-D system of differential equations. I am interested in a numerical simulation. A phase diagram would be nice too. I've tried the standard bag of tricks, but remain quite lost.

Hi,

I have a dual processor computer and I am using Maple 8 (because it is much faster than Maple 11) but I noticed that Maple 8 only maxes out one processor and doesn't use both.  I am using (unfortunately) Windows Vista.  I would appreciate any suggestions.

I also have a single 2.3 GHz processor at home with XP so I'll give that a try.

Thanks

Hi.

I think there is a problem with arrays. When i define an array like this:

A := {1,12}
Then it works fine as you can see:
print(A[1])=1
print(A[2])=12

but if i do it like this:
A := {1.1,12}
Then the results is reversed:
print(A[1])=12
print(A[2])=1.1

I'm running Maple 11 and updated to the 02 patch.

When I try to integrate a function,Maple returns a summation sign and underneath this sign is the expression R= RootOf (      ),where the bracket contains a cubic polynomial written in terms of Maple's internal default variable _Z.  Why can't Maple simply evaluate the roots of this cubic equation and return the value to me? What do I have to do to force Maple to return the desired result? 

AntipodeanMan

Hi there,

fsolve fails me, for the first time. I have this very messy expression, which comes out of a cubic equation. It must have a zero. I plot it and the graph, smooth, shows a zero between 16.4 and 16.5, but maple's fsolve fails to find it, why's that? The slope of the function is very flat near the zero. I tried to tell maple the solution is between 16.4 and 16.5, to no avail.

Any advice will be much appreciated. The following code tells it all.

many thanks,

Patrick.

I am having problems using implicitplot.  I run this code and it worked and today I tried it again and it gives me the following:

with(plots,implicitplot);

implicitplot(0=int(erf(  (T-e*t)/sqrt(2)  )*t^2*exp(-t/2),t=0..infinity),e=0..1,T=0..10);

Error, (in plots/implicitplot) invalid input: the following extra unknowns were found in the input expression: {t}

The weird thing is that this worked before (took about 10min though) and now it isn't.  Any suggestions?

Thanks

May be that some other people want to use pattern-matching techniques in wrong ways or contexts. What I am interested in is much simpler and clear.

Using dsolve gives the incorrect solution unless you force it to use Laplace transforms. 

Notice that Y5 is the correct solution, not the Y coming from dsolve.

DE17:=diff(y(t),t$2)+y(t)=Dirac(t-Pi)+Dirac(t-2*Pi)+Dirac(t-3*Pi);
Y:=dsolve({DE17,y(0)=0,D(y)(0)=0},y(t));
plot(rhs(Y),t=0..6*Pi);
with(inttrans):
Y2:=laplace(DE17,t,s);
Y3:=solve(Y2,laplace(y(t),t,s));
Y4:=subs({y(0)=0,D(y)(0)=0},Y3);
Y5:=invlaplace(Y4,s,t);
plot(Y5,t=0..6*Pi);
 

Anybody run into this problem before?

View 8340_helpweaklynonlinear.mw on MapleNet or Download 8340_helpweaklynonlinear.mw

A colleague recently showed me some strange behavior when trying to plot vertical lines. The following works to create the unit square:

plot( [x=0,x=1,0,1], x=0..1, y=0..1, color=black, axes=none ); # OK

But doubling the size in each direction does not produce a square:

plot( [x=0,x=2,0,2], x=0..2, y=0..2, color=black, axes=none ); # BAD

The vertical lines extend only up to y=1, not y=2 as requested. The next command shows that vertical lines at the boundary are treated differently.