Re: Combined plot

[Markus Mützel]

Am 27. Januar 2021 um 08:59 Uhr schrieb "Blaz":
> Hello
> I have two issues to solve in Octave.
>
> First issue
>
>  I have a vector [x]. Is there a simple way to create two new vectors (e.g.
> xodd and xeven)? xodd is (obviously) composed from odd index-es of x and
> xeven from even ones. I have written the code below, but it fills the blanks
> with zeros, which is not ok. I would like to have only the extracted values
> in new vectors.
>
> t = [0:0.001:0.03];
> x = sin(2*pi*50*t);
> for i=1:length(t)
>   if rem(i,2) == 0
>     xeven(i)=x(i);
>   end
>   if rem(i,2) == 1
>     xodd(i)=x(i);
>   end
> end
>

You could use this:
xeven = x(2:2:end);
xodd = x(1:2:end);


> Second issue
>
> When I do have x, xodd and xeven vectors properly calculated I wish to plot
> them as following
>
> 1. x as a simple plot (x) on first diagram (e.g . subplot (311))
> 2. x as a simple plot (x) and xeven as arrows between x-axis and plotted x
> curve (subplot 312)
> 3. x as simple plot(x) and xodd as arrows between x-axis and plotted x curve
> (subplot 313)
>
> I tried with bar (xodd) and bar(xeven), but I would like to plot the arrows
> instead of bars.
>

`quiver` draws arrows. Maybe you could use that function for your purposes.

HTH,
Markus