[scilab-Users] problem with scilab

[arnaud dujeu]

In fact I have try several methods and no one is working, do you know if it's possible with scilab to plot alpha(t) and alpha'(t) when the differential equation is like : alpha''(t) = A*(1-sin(alpha(t)))/(pi/2-alpha(t))-B*(alpha'(t))^2/(pi/2-alpah(t))
What would be the function to use ?


Date: Thu, 21 Jul 2011 14:06:16 +0200
From: Serge.Steer at inria.fr
To: users at lists.scilab.org
Subject: Re: [scilab-Users] problem with scilab



  


    
  
  
    

    What do you mean by "it
      doesn't work." error message?, unexpected results?

    

    I was not able to run it because g R DeltaP and B are undefined.

    

    

    Serge Steer

    INRIA

    

    Le 21/07/2011 11:25, arnaud dujeu a écrit :
    
      
      
        Hi,
        

        
        I've got a problem to solve a non linear differential
          equation, which is :
        

        
        y1'=A*(1-sin(y2))/(pi/2-y2)-B*y1^2
        y2'=y1
        

        
        

        
        I'm using ode : 
        

        
        
          function [Xprime]=VanDerPol(t, X)
 
 Xprime(1) = X(2)
 Xprime(2) = g/R*(1-sin(X(1)))/(%pi/2-X(1))-deltaP/(B*(%pi/2-X(1)))
 
endfunction

 t=linspace(0,4,3000); X0=[85*%pi/180;0];
 [u]=ode(X0,0,t,VanDerPol);

plot(t,u(1,:)*180/%pi,'r')
 plot(t,R*u(2,:))
          

          

          but it doesn't work.
          

          Do you know why?
          

          Best regards.
        
      
    
    
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.scilab.org/pipermail/users/attachments/20110721/2ef61a83/attachment.htm>