There is no other way, in general, to plot symbolic values (except choosing numbers other than 1, 3, 4), plot is a numerical procedure in Maple. K can be added to the tickmarks; for example, 1=K after 0=0, and view of the y-axis in this case can be increased to, say, 0..1.5 instead of 0..1 - you can experiment to find a better looking value. By the way, according to Maple calculations, it should be K*Pi instead of K, but that depends on the units.

P.S. Did you use Classic Maple or Standard? What version?

__________
Alec Mihailovs
http://mihailovs.com/Alec/

op is a sequence of terms, type ?op in Maple for examples. If it used with indexes, such as op(1,a) or op([2,1,2],a), then the corresponding subterms are selected. In the last example,

s:=op(S);

  s := 1.500000000 Dirac(w - 3.), 2. Dirac(w + 1.), 3. Dirac(w + 4.),

        1.500000000 Dirac(w + 3.), 2. Dirac(w - 1.), 3. Dirac(w - 4.)

op(1,s[1]);

                             1.500000000

op([2,1,2],s[1]);

                                 -3.

?map is also useful in this context.

__________
Alec Mihailovs
http://mihailovs.com/Alec/

I modified the above code to use an array little bit:

a[1]:=w1+w2-w3:
a[2]:=-w1+2*w2:
a[3]:=2*w1-w2-2*w3:
a[4]:=-w1+w2-w3:
a[5]:=-w1+w2+w3:
b:=w3>w2,w2>w1,w1>0,w2-w1>w3-w2:
max(a) assuming b

I faced the following error:
;Error, (in assuming) when calling 'simpl/max'.
Received: 'arguments must be of type algebraic'

Any suggestion?
Thanks,

We just found how to find max and min.

What about sort?
Can we sort the numbers in "a" variable?

Using an array of "a" variable.. (ie. a[0], a[1] ...)

Thanks,

I made a tiny mistake. That is why proper label 
for X-axis didn't show up. :-) I now can see proper labels.

======>
Question 1:
As described the above, you assmed a=[-5,-3,1,2,4].
Then without removing the op(-a) as seen in my code, 
how could I modify your code to plot -5,-3,1,2,4 only rather than plotting its symmetry values 5,3,-1,-2,-4 ?


======> 
Question 2:
when we draw "positive" side plot using "pos", its first point is close to Y-axis. 
How can I make proper distance from Y-axis from the first point? 
Using "view" option ???

=====>
Question 3:
How can I count paticular numbers?
ie) Let's assume we have the following data
a:=[1, 1, 1, 3, 4, 7, 3.2, -1, -1, 5 1, -1]:

How can I count how many both 1 and -1 has in the array?
I expect to have 7 counts.

=====>
Question 4:
I have a data such as:
a:=[1,2,3,4,1,5,2,2]:
As seen in the array, the number "1" has twice and "2" has three times. What I want is that
(1) Find true or false from the array data.
If any number is duplicated in the array, 
it is "true" otherwise "false"

(2) Then find what number is duplicated.
From the above example, 
duplicated numbers are "1" and "2".


=====>
Question 5:
I made the following simple expression.
restart:
X:=array(1..12):
for i to 12 do
X[i]:=i:
end do:
print(X);
nops(X);

Its result came out:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
size:=1

How can I print the array size to be 12?
Somehow using the "nops" doesn't give me a correct size.

Let's assume the X is Table and not an array.
In the case, how can I display number of contents in the table?
i.e)
for i to 12 do
X[i]:=i:
end do:
print(X);
nops(X);

Its result:
TABLE([1 = 1, 2 = 2, 3 = 3, 5 = 5, 4 = 4, 7 = 7, 6 = 6, 10 = 10, 11 = 11, 8 = 8, 9 = 9, 12 = 12])
size:=1

** Still give me 1 for table size. I expect 12.

======>
Question 6:
I sorted the "a" array under assumptions and its result came out.
Used code:
a:=[w1+w2-w3,
    -w1+2*w2,
    2*w1-w2-2*w3,
    -w1+w2-w3,
    -w1+w2+w3]:
 b:=w3>w2,w2>w1,w1>0,w2-w1>w3-w2:


Sort result becomes:
2*w1-w2-2*w3, -w1+w2-w3, w1+w2-w3, -w1+2*w2, -w1+w2+w3

If we plot original values (without symmetry values),
points in X-axis perfectly match with the sort result !! :-)

Let's assume we draw the plot in positive side only using your "pos" procedure.
Order of points in X-axis plot now becomes:
w1+w2-w3, w1-w2+w3, -w1+2*w2, -w1+w2+w3, -2*w1+w2+2*w3

As seen, its order is now different from the result by 
previous "sort" function and the negative symbol becomes positive in positive plot.

How can I modify the previous "sort" command to match with the order of positive points and symbols in X-axis plot?

Thanks!