[Scilab-users] ?==?utf-8?q? plotting a function that changes with x

[Lloyd Judd]

Merci Phillip,Antoine,
Now I have something very close to what I am looking for
Thanks for your help
regards
Lloyd

------ Original Message ------
From: "P M" <p.muehlmann at gmail.com>
To: "Users mailing list for Scilab" <users at lists.scilab.org>
Sent: Monday, 10 Feb, 2020 At 9:46 AM
Subject: Re: [Scilab-users] ?==?utf-8?q? plotting a function that 
changes with x


Hi,

with the if-loop-approach you probably thought about this:

x=(0:1:72)
for i=1:length(x)
     if ((x(i)<18) == %T)                   // elementwise comparison
         then y(i) = sin(x(i)*%pi/24)
     else
         y(i)= 0.1*x(i)
     end
end
plot2d(x,y,2)However it's a if-loop within a for loop...
Best regards,
Philipp


Am So., 9. Feb. 2020 um 10:34 Uhr schrieb Antoine Monmayrant 
<amonmayr at laas.fr <mailto:amonmayr at laas.fr> >:
Hello,

  I think that (x>18) is not doing what you think it does.
  See below two options to define  y piecewise.
  Hope it helps,

  Antoine

  ----------------------

  //your code
  clf
    x=(0:1:72)
  // here you x<18 is not what your think (it's a boolean vector)
  if x<18
  then y = sin(x*%pi/24)
  else
       y= 0.1*x
  end
  plot2d(x,y,2)

  // two options

  // using the fact that x>18 is converted into
  // 1 when the condition is true
  // 0 when the condition is false
  y2 =  sin(x*%pi/24).*(x>18) + 0.1*x.*(x<=18);

  plot(x,y2,"ro");

  // using a range of indices & find
  y3=0.1*x;
  inds=find(x>18);
  y3(inds)=sin(x(inds)*%pi/24);

  plot(x,y3,"g");

  ----------------------




  Le Dimanche, Février 09, 2020 08:56 CET, Lloyd Judd 
<ltjudd at bigpond.com <mailto:ltjudd at bigpond.com> > a écrit:

  > Hello, 
  > I am trying make a plot, the function of which changes depending on 
the
  > value of x,. What I am really trying to do is to simulate solar 
panel
  > out put where it roughly follows a sine  function during daylight 
but is
  > basically zero from sunset to sunrise, and then later overlay that 
with
  > the demand curve. But I am still experimenting with the code at this
  > stage.
  >  I tried all different ways;  using the "function" command and the 
"plot
  > 2d" command . It only ever seems  to plot the last argument in the 
"if
  > then else" statement.
  > For example with this code;
  > clf
  >    x=(0:1:72)
  >   if x<18
  >       then y = sin(x*%pi/24)
  >   else
  >       y= 0.1*x
  >    end
  >   plot2d(x,y,2)it only plots  the y=0.1x partConversely if I put the
  > sine function under the "else" statement, it only plots the  sin
  > function.clfx=(0:1:72)
  > if x<18 then
  >      y=0.01*x
  > else
  >      y=sin(x*%pi/24)
  > end
  >   plot2d(x,y,2)What is the best way to plot a function that changes
  > depending on the range of x?Thanks and regardsLloyd Judd
  >

  _______________________________________________
  users mailing list
  users at lists.scilab.org <mailto:users at lists.scilab.org>
  http://lists.scilab.org/mailman/listinfo/users 
<http://lists.scilab.org/mailman/listinfo/users>

  _______________________________________________
users mailing list
users at lists.scilab.org
http://lists.scilab.org/mailman/listinfo/users 
<http://lists.scilab.org/mailman/listinfo/users>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.scilab.org/pipermail/users/attachments/20200211/48764985/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Capture truncated sine curve.JPG
Type: image/jpeg
Size: 121905 bytes
Desc: not available
URL: <https://lists.scilab.org/pipermail/users/attachments/20200211/48764985/attachment.jpe>