THanks for solutions. But why can't one  use rtable_scanblock to do this? or rather, how can one use rtable_scanblock for this? Just to learn.

I looked at the link provided above, and I also liked Preben answer there, I applied it to this problem, like this:

ind:=Matrix(2,3,(i,j)->if A[i,j]>=3 then [i,j] else NULL end if);
convert(ind,list);

@Kitonum 

thank you, but these really searching using explicit looping. ofcourse one can always use loops to do the search. But I prefer not to do that unless there is no other option.

@oldstudent 

Please do not get me started on Maple help !  When I search for something on Maple on google (since it is much easier to do that than use Maple itself to search for command or topic), all the Maple help pages on the net are written using some strange notation and they are put there as images!  So this mean one can't even copy a command they see to use. So all this time wasted searching, and at the end one can't even copy the command shown.

Not only that, the pages themselves are so hard to read. The images are low resolution. I have no idea how a company can even produce such help pages and publish them to the public to see. I myself would be ashamed to publish such terrible looking help pages on my own web site and I am just a student. How can a large software company do this and consider it as acceptable is beyond me.

An example:

http://www.maplesoft.com/products/maple/new_features/maple17/signal_processing.aspx

@Alejandro Jakubi 

Thanks for the link. I am glad to see I am not the only person to rample about this. (btw, it seems those pages have been reformatted? The text all just flows from top to down with no paragraph break and no new lines anywhere. It seems like the original post was copied and repasted removing all spaces, making them hard to read)

But I really do not buy this "organic ecosystem" idea at all. In Engineering, a product can be build from many different components made by many different manufacturers and different organizations located all over the world, and then assembled in one place and everything comes out that fits just right.

Take Boeing 777 for example. There are over 100 different companies that actually build it. The engine can be build somewhere, the wings somewhere else, and so on. Yet, they all fit well and work together. Look at the iPhone, its parts are build by dozens of different companies.

Just because a product is built by different people all over the world, does not means that there should not be well designed specifications and discipline to insure that the final product comes out as optimal as it should.

(Btw, I forgot to mention the largest  duplication in Maple. The UI itself is duplicated as well! Worksheet UI, Classical UI, Document UI.  Yet, all have many usability issues as is well known.  I wonder if this is also due to this organic ecosystem idea).

@acer 

forgot square brackets around entries in your Vector call

I did not even think I need [], since I allready told it is a Vector[row]  that I want there!  But I am newbie, and getting used to this notation. I think Matlab is much easier for this sort of thing.

I do not mind using <<>> except  it confuses me sometimes, since <<1,2,3>> is a column! where one would expect it to be row due to the use of comma.

While Matrix([[1,2,3]]) is a row. So we see that the use of comma is flipped between <<>> and between [[ ]].

That is why I wanted to stick to one notation, else I go crazy.  Of all the software I tried, only Matlab got it right when it comes to working with vectors and matrices. (but that is all what it got right).

@acer 

thanks, This worked. I also added legend (was bit of struggle as never used this before). Here is the final plot

restart;
alias(DS=DynamicSystems):
H:=(w,zeta)->w^2/(s^2+2*zeta*w*s+w^2):
sys:= (w,zeta)->DS:-TransferFunction(H(w,zeta)):
zetaValues := [seq(i,i=0.1..1.2,.2)]:
sol:= map(z->DS:-Simulate(sys(1,z),Heaviside(t)),zetaValues):
c:=ColorTools:-GetPalette("Niagara"):
plots:-display(seq(plots[odeplot](sol[i],t=0..10,color=c[i],legend=typeset(zeta,"=",zetaValues[i]),legendstyle=[location=right]),i=1..nops(zetaValues)),gridlines=true,
title="step response for different damping ratios",labels=[typeset(t),typeset(y(t))]);

@Carl Love 

when I tried your answer it did not work. I noticed now you had just forgtton some line of code. Yes, you solution works very well also. Thanks.,

@Preben Alsholm 

good solution also.

I wonder why inttrans[laplace](g(t),t,s) when it returns unevaluated doesn't return inttrans[laplace](g(t),t,s) instead of laplace(g(t),t,s).

yes, this is the source of all the trouble. If Maple left inttrans[laplace] in there as it was typed in, then the problem will not show up at all. Is this a bug? At least it is not what one would expect.

@Carl Love 

The restart command should always go in its own execution group

This seems too restrictive. Since now I have to hit the return key 2 times to execute some code fragment in its own group. One time for the restart, and another for the code itself.

I always like to have restart() at the top in the same group when testing something and do one return on the whole thing. May be I need to buy a better keyboard with bigger return key to use Maple, since I will be hitting the return key much more in this case :)

@Carl Love 

thanks, but you solution did not evaluate it for me:

restart;
f:=t->piecewise(t<0,0,t>=0 and t<z,t,t>z,z):
r:=convert(f(t),Heaviside):
eval(subs(z= 0.5, laplace= inttrans[laplace], r));

I am using Maple 18 on windows.

@Markiyan Hirnyk 

I do not have a bigger example. This is the only one I have which just same up and I found I am forced to load the package. I am learning Maple, and newbie, so I assumed more examples could come up in the future.

It seems the only solution then is to do assumptions and anything else needed before hand, so to avoid an expression coming up not evaluated as the case was here. Ok. Will live with this.

@Markiyan Hirnyk 

But as I said, I know I could add an assumption and do it:

(I can handle this with assumptions, but this is just an example).

And this is how I do it now allready.

As I said, this was just an example. Suppose I do not want to use assumptions and use some specific value at some later point? The above case can show up in different location and different cases. You might argue that this is too much of a contrived example and will not come up in practice, and you could be right. But it came with with me now when I was trying to solve with Laplace and did not work, and then tried to do subs after the fact.

@acer 

I do not like solution that require manual mouse/click/menu actions. I want programmable solution, so I can write the code once and run it and not have to keeping clinking and pulling menus each time. Thanks any way, this was just something I noticed. I do not think I'll be using Bodeplot much any more in Maple. I just wanted to try it. It has many other problems and I'll get tired just to try to enumerate them. So I think I will stop here and go on to something else.

@acer 

In this example you have forced one part of the size to 300, but then complain that the aspect ratio is not right.

I changed one size and used default for the other  size=[300,"default"]?

So that the other dimension will automatically change keeping the same aspect ratio.  At least that is what thought should happen. You used default also for one size yourself here:  size=[default,0.7]

In Mathematica, there is an option called AspectRatio that one can adjust themselves. I am simply asking if there is such an option in Maple plots and graphics. How does one even query what aspect ratio is used by a plot in Maple? In Mathematica one can query the aspect ratio used and changed it if needed.

@Carl Love 

Thanks. Is this documented anywhere? I spend maybe  30 minutes looking at examples, and none of them even mentioned the exports(sys) and how to read these fields inside.

Very few examples to help one how to use it.