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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) INRIA - 
// 
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution.  The terms
// are also available at    
// http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt


function [y,x]=csim(u,dt,sl,x0,tol)
//Syntax:
//  [y [,x]]=csim(u,dt,sl,[x0]) 
// simulation of the controlled linear system sl.
// sl is assumed to be a continuous-time system.
// u is the control and x0 the initial state.
//
//u can be:
// - a function 
//    [inputs]=u(t)
// - a list
//    list(ut,parameter1,....,parametern) such that
//    inputs=ut(t,parameter1,....,parametern)
// - the character string 'impuls' for impulse response calculation
//    (here sl is assumed SISO without direct feedthrough and x0=0)
// - the character string 'step' for step response calculation 
//    (here sl is assumed SISO without direct feedthrough and x0=0)
//dt is a vector of instants with dt(1) = initial time
//                   that is:           x0=x
//                                          dt(1)
//
//y matrix such that:
//  y=[y       y  ...  y     ]
//      dt(1)   dt(2)   dt(n)
//x matrix such that:
//  x=[x       x  ...  x     ]
//      dt(1)   dt(2)   dt(n)
//
//See also:
// dsimul flts ltitr rtitr ode impl
//!

  [lhs,rhs]=argn(0)
  //
  if rhs<3 then error(39),end
  sltyp=typeof(sl)
  if and(sltyp<>['state-space' 'rational']) then 
    error(msprintf(_("%s: Wrong type for input argument #%d: %s data structure expected.\n"),"csim",3,"syslin"))
  end
  if sltyp=='rational' then sl=tf2ss(sl),end
  if sl.dt<>'c' then 
    warning(msprintf(gettext("%s: Input argument %d is assumed continuous time.\n"),"csim",1));
  end
  //
  [a,b,c,d]=sl(2:5);
  if type(d)==2&degree(d)>0 then 
    d=coeff(d,0);
    warning(msprintf(gettext("%s: Direct feedthrough set to its zero degree coefficient.\n"),"csim"));
  end
  [ma,mb]=size(b);
  //
  imp=0;step=0
  text='if t==0 then y=0, else y=1,end'
  //
  select type(u)
  case 10 then //input given by its type (step or impuls)
    if mb<>1 then error(95,1);end;
    if part(u,1)=='i' then
      //impuse response
      imp=1;
      if norm(d,1)<>0 then
	warning(msprintf(gettext("%s: Direct feedthrough set to zero.\n"),"csim"));
	d=0*d;
      end;
    elseif part(u,1)=='s' then
      step=1
      if norm(d,1)<>0 then
	warning(msprintf(gettext("%s: Direct feedthrough set to zero.\n"),"csim"));
	d=0*d;
      end;
    else
      error(msprintf(gettext("%s: Wrong value for input argument #%d: Must be in the set {%s}.\n"),"csim",1,"""step"",""impuls"""))
    end;
    deff('[y]=u(t)',text);
  case 11 then //input given by a function of time
    comp(u)
  case 13 then //input given by a function of time
  case 1 then //input given by a vector of data
    [mbu,ntu]=size(u);
    if mbu<>mb | ntu<>size(dt,'*') then 
      error(msprintf(gettext("%s: Incompatible input arguments #%d and #%d: Same column dimensions expected.\n"),"csim",1,2))
    end
  case 15 then  //input given by a list: function of time with parameters
    uu=u(1),
    if type(uu)==11 then 
      comp(uu),
      u(1)=uu,
    end
  else error(44,2)
  end;
  //
  if rhs==3 then x0=sl(6),end
  if imp==1|step==1 then x0=0*x0,end
  nt=size(dt,'*');x=0*ones(ma,nt)

  [a,v]=balanc(a);
  v1=v;//save for backward transformation
  
  //apply transformation u without matrix inversion
  [k,l]=find(v<>0) //get the permutation
  
  //apply right transformation 
  v=v(k,l);//diagonal matrix
  c=c(:,k)*v; 
  //apply left transformation 
  v=diag(1 ./diag(v));b=v*b(k,:);x0=v*x0(k)
  
  [a,v2,bs]=bdiag(a,1);b=v2\b;c=c*v2;x0=v2\x0;
  //form the differential equation function
  if type(u)==1 then
    //form a continuuous time interpolation of the given data
    ut=u;
    if min(size(ut))==1 then ut=matrix(ut,1,-1),end
    deff('[y]=u(t)',['ind=find(dt<=t);nn=ind($)'
		     'if (t==dt(nn)|nn==nt) then '
		     '   y=ut(:,nn)'
		     'else '
		     '   y=ut(:,nn)+(t-dt(nn))/(dt(nn+1)-dt(nn))*(ut(:,nn+1)-ut(:,nn))'
		     'end']);
    deff('[ydot]=%sim2(%tt,%y)','ydot=ak*%y+bk*u(%tt)');
  elseif type(u)<>15 then
    deff('[ydot]=%sim2(%tt,%y)','ydot=ak*%y+bk*u(%tt)');
    ut=ones(mb,nt);for k=1:nt, ut(:,k)=u(dt(k)),end
  else
    %sim2=u
    tx=' ';for l=2:size(u), tx=tx+',%'+string(l-1);end;
    deff('[ydot]=sk(%tt,%y,u'+tx+')','ydot=ak*%y+bk*u(%tt'+tx+')');
    %sim2(0)=sk;u=u(1)
    deff('[ut]=uu(t)',...
	 ['['+part(tx,3:length(tx))+']=%sim2(3:'+string(size(%sim2))+')';
	  'ut=ones(mb,nt);for k=1:nt, ut(:,k)=u(t(k)'+tx+'),end'])
    ut=uu(dt);
  end;
  
  //simulation
  k=1;
  for n=bs',
    kk=k:k+n-1
    ak=a(kk,kk)
    bk=b(kk,:)
    nrmu=maxi([norm(bk*ut,1),norm(x0(kk))])
    if nrmu > 0 then
      if rhs<5 then
	atol=1.d-12*nrmu;rtol=atol/100
      else
	atol=tol(1);rtol=tol(2)
      end
      x(kk,:)=ode('adams',x0(kk),dt(1),dt,rtol,atol,%sim2)
      if imp==1 then x(kk,:)=ak*x(kk,:)+bk*ut,end
    end;
    k=k+n
  end;
  if imp==0&step==0 then y=c*x+d*ut,else y=c*x,end
  if lhs==2 then x=v1*v2*x,end
endfunction