@Saha To apply the sin command to x you need to enter it as,

   sin(x)

without spaces between the "sin" and the "(" if you are using 2D Input mode.

@Danish Toheed What are you trying to plot? I mean, what are the coordinates in some point-plot supposed to represent? The plotted point should each have two coordinate values -- for the horizontal and vertical positions.

It's not clear what your code is trying to accomplish. What's the purpose of the inner do-loop?

Your attachment seems to have been last saved in Maple 2021, but earlier you indicated that you were using Maple 18. Which do you use?

Why have you written,
   sin (x)
with a space, in 2D Input mode, instead of,
   sin(x)
?

Are you trying to copy some code written elsewhere? If so, was it in 1D plaintext, or 2D Input? If the former, then I suggest you use the same mode of entry.

@Saha Let's start again.

Now you've entered,
    sin (x)
which gets parsed as  sin * x , ie. a multiplication.

Again, did you intend the more usual,
   sin(x)
?

@jmakinde In your second attempt you did not load odeplot from the plots package (nor call it by its full name, plots:-odeplot).

You changed Tom's code, where he loaded the plots package.

Let's start off slow, with some basic syntax.

Did you intend
   sin(x)
where you had entered (in 2D Math mode)
   sin x
?

@Axel Vogt Nicely done.

@pik1432 The other answers all used your additional helper equation eq_Dx, whereas the answer I gave did not need it. (I was supposing that you might have created that additonal equation manually.)

But, given your additional eq_Dx, then your target can be obtained by,

@mmcdara You're a little close (IMO) to suggesting that it is the imaginary unit I in particular that is the cause of your difficulty, and that would not be accurate.

In fact similar difficulties exist for compound products involving several extra multiplicands in the coefficient, even without I being present.

As sursumCorda has explained, it is due to the fact that your target term is not structurally present in the rhs.

Consider the example below. The term c*Int(f(x),x), ie. the lhs(eq), is not structurally present in rhs(eq). That is the case, even though the printing gives that appearance.

The "sub-product" c*Int(f(x),x) is not an actual structural component of the product 2*b*c*Int(f(x),x).

@tomleslie I asked whether he wanted just some kind of reflection (for which I too would have reflected/other, and spoofed the tickmarks, etc).

But the OP wrote, "However, I will like the horizontal axis to remain 0 to 15 but on the vertical axis, instead of having it going from 1 down to zero, I want it to be from 1 going up to 2."

What do you imagine that is supposed to mean?

I can concoct several different kinds of mapping that do that to an arbitrary curve, but it's unclear whether any of them are what's wanted. The goal is -- as yet -- not adequately specified.

@jmakinde The vertical position of the curve, at any horizontal value 't', is a consequence of the mathematical nature of the function. It's a math aspect, not a Maple aspect.

Suppose I plot A=t^2 between t=0 and t=3. It ascends from A=0 to A=9. How should I respond to the request that instead it descends from A=18 down to A=9?

@jmakinde I don't understand what you're saying, sorry.

Do you want to change the values of the curve?

Can you not provide some other curve/function, and show an analogous (but unambiguous) result with a similar kind of mapping?

@jmakinde I don't really understand what you mean, sorry.

I'll note that you have not provided your actual ODE. Is there a reason for that?

Are you trying to say that you want the values reversed on the x-axis, ie. going from say 15 to zero and one moves from left to right?

@jmakinde For asterisk or cross you would use style=point (instead of linestyle=dot and the default style=line).

For example,

plots:-display(
  plots:-textplot([4.4,120,N(t)]),
  plots:-odeplot( sol7, [t, N(t), color = red,
                  style=point, symbol=asterisk, symbolsize=12],
                  0 .. 5, numpoints=30),
  labels = [t,N(t)], size=[475,400] );

The file has not been attached.