REszesc

rstanu6E = function(t, x, a){
  u = 1
  dx1=(1/20)*u - (1/20)*x[2]
  dx2=(3/20)*u + x[1] - (9/20)*x[2]
  list(c(dx1,dx2))
}

rstanu6Esin = function (t, x, a){
  u=sin(0.5*t)
  dx1=u-x[2]/20
  dx2=9*u-((9*x[2])/20)+x[1]
  list(c(dx1,dx2))
}







rstanu6E = function(t, x, a){
  u = 1
  dx1=(1/20)*u - (1/20)*x[2]
  dx2=(3/20)*u + x[1] - (9/20)*x[2]
  list(c(dx1,dx2))
};

rstanu6Esin025t = function (t, x, a){
  u=0.025*t
  dx1=(1/20)*u - (1/20)*x[2]
  dx2=(3/20)*u + x[1] - (9/20)*x[2]
  list(c(dx1,dx2))
}

rstanu6Esin = function (t, x, a){
  u=sin(0.5*t)
  dx1=(1/20)*u - (1/20)*x[2]
  dx2=(3/20)*u + x[1] - (9/20)*x[2]
  list(c(dx1,dx2))
}

eksp1 = function(x0){
  t = seq(0, 10, 0.01)
  out1 = ode(x0, t, rstanu6E, NULL)
  out2 = ode(x0, t, rstanu6Esin025t, NULL)
  out3 = ode(x0, t, rstanu6Esin, NULL)
  par(mfrow=c(2,2))
  y1 = out1[,3]
  y2 = out2[,3]
  y3 = out3[,3]
  plot(t,y1,type='l',col='red',xlab='t',ylab='y',main='wykres y(t) u = 1')
  lines(t,y2,type='l',col='blue',xlab='t',ylab='y',main='wykres y(t) u = 0,025t')
  lines(t,y3,type='l',col='green',xlab='t',ylab='y',main='wykres y(t) u = sin(0,5t)')
  #plot(out1[,2],out1[,3],type='l',col='blue',xlab='x1',ylab='x2',
  #     main='portret fazowy')
}
eksp1(c(0,0))