Matlab ode15s change parameter value at specific time during solution

Question

gorilla3 2018-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/415784-matlab-ode15s-change-parameter-value-at-specific-time-during-solution

评论： Torsten 2018-8-22

I'm trying to change the value of my variable Pin at specific points in time during the ode15s solution, in order to evaluate the dynamic response. But I get the error:

Error using odearguments (line 83)
The last entry in tspan must be different from the first entry.

I believe the error is somewhere here:

t_start=0;
    t=t_start;
    y=cond;
      while idx_seg< length(t_seg)
          idx_seg=idx_seg+1;
          t_end=t_seg(idx_seg);    
      [t_sol,y_sol]=ode15s(@(t,y)f1_v1,[t_start, t_end],y(end,:));
      t = [t; t_sol(2 : end)];
      y = [y; y_sol(2 : end, :)];
      t_start = t_end;
      end

Here's the full code:

      function [t,y]=f2_v4_21_08_18(cond, t_seg, Pin)
           % -----Constants -----
               N=3.38*10^6; k=2.96*10^-7; alphat=2.6*10^-5; chb=0.2; M=30*10^-9; K=5*10^(-8)*10^-3; H=0.42; S0=0.98; 
      bp=0.8; ro=1040*10^6; 
      Ey=10^4*0.00750062; 
      v=3* 7.5*10^-6; 
      r=[0.0119850000000000;0.00958500000000000;0.00764000000000000;0.00604000000000000;0.00473000000000000;0.00366000000000000;0.00400000000000000;0.00575500000000000;0.00726500000000000;0.00889500000000000;0.0107250000000000;0.0128500000000000;0.0153850000000000]; %mm
      L=[1.27076497943190;0.932650928622621;0.544932761536915;0.303082765473283;0.161799106136796;0.155424891414508;0.245072221621871;0.475103125625241;0.273016623935407;0.427646038844292;0.634082325832342;0.846354695529459;0.938696601022114]; %mm
      h=[0.00484000000000000;0.00425000000000000;0.00381000000000000;0.00349000000000000;0.00327000000000000;0.00314000000000000;0.000309000000000000;0.00115000000000000;0.00145000000000000;0.00178000000000000;0.00215000000000000;0.00257000000000000;0.00308000000000000];%mm
      mu=[1.19409872390289e-05;1.12760032450214e-05;1.06583134073916e-05;1.00804835896938e-05;9.56162410894012e-06;9.20633512007761e-06;9.29628357913371e-06;9.96996247072375e-06;1.05291656347798e-05;1.10660983739492e-05;1.16035344790804e-05;1.21594980256614e-05;1.27473361251949e-05]; %mmHg*s
      R= [1.8728    3.1728    4.3411    5.8457    7.8705   20.3059   22.6623   10.9961    2.6277    1.9250    1.4161    0.9612    0.5439]; %[mmHg*s/ml]
      pdrop=[0,6.93,5.87,4.02,2.70,1.82,2.35,2.62,1.27,0.61,0.89,1.31,1.78,2.01];
      n=[1,2,4,8,16,32,64,32,16,8,4,2,1]; 
      %%%%%
      idx_seg=0;
      function dy= f1_v1(t,y)
      dy=zeros(13,1);
      pt1=y(1); pt2=y(2); pt3=y(3); pt4=y(4);  pt5=y(5);  pt6=y(6);  pt7=y(7);  pt8=y(8);  pt9=y(9);  pt10=y(10);  pt11=y(11);  pt12=y(12);  pt13=y(13);
       % -----Constants -----
  ...
      R= [1.8728    3.1728    4.3411    5.8457    7.8705   20.3059   22.6623   10.9961    2.6277    1.9250    1.4161    0.9612    0.5439]; %[mmHg*s/ml]
      pdrop=[0,6.93,5.87,4.02,2.70,1.82,2.35,2.62,1.27,0.61,0.89,1.31,1.78,2.01];
        for i=1:1:14
          if i==1
              pb(i)=Pin(idx_seg);
          else
          pb(i)=pb(i-1)-pdrop(i);
          end
          pb(i)=pb;
        end
      diffp=diff(pb)*(-1);
      pb_s=[pb(1)+pb(2);pb(2)+pb(3);pb(3)+pb(4);pb(4)+pb(5);pb(5)+pb(6);pb(6)+pb(7);pb(7)+pb(8);pb(8)+pb(9); pb(9)+pb(10);pb(10)+pb(11);pb(11)+pb(12);pb(12)+pb(13);pb(13)+pb(14)];
      for z=1:1:14
          S(z)=(((pb(z)^3+150*pb(z))^(-1) *23400)+1)^(-1);
      end
      deltaS=diff(S)*(-1);
      for j=1:1:13
          kin=v;
          compl(j)=((3*pi*L(j)*r(j)^3)/(2*Ey*h(j)) )*10^-3; 
          Vb(j)=(compl(j)/2)*pb_s(j); %[ml]
          q(j)=diffp(j)/R(j);
          Vt(j)= chb*H*q(j)*deltaS(j)/M;
      end
      %%differential eq
      dpt1=1/(alphat*Vt(1))*( (2*pi*K*r(1)*L(1))/h(1) *(1/2*(pb(1)+pb(2)) -pt1) -M*Vt(1));
      dpt2=1/(alphat*Vt(2))*( (2*pi*K*r(2)*L(2))/h(2) *(1/2*(pb(2)+pb(3)) -pt2) -M*Vt(2));
      dpt3=1/(alphat*Vt(3))*( (2*pi*K*r(3)*L(3))/h(3) *(1/2*(pb(3)+pb(4)) -pt3) -M*Vt(3));
      dpt4=1/(alphat*Vt(4))*( (2*pi*K*r(4)*L(4))/h(4) *(1/2*(pb(4)+pb(5)) -pt4) -M*Vt(4));
      dpt5=1/(alphat*Vt(5))*( (2*pi*K*r(5)*L(5))/h(5) *(1/2*(pb(5)+pb(6)) -pt5) -M*Vt(5));
      dpt6=1/(alphat*Vt(6))*( (2*pi*K*r(6)*L(6))/h(6) *(1/2*(pb(6)+pb(7)) -pt6) -M*Vt(6));
      dpt7=1/(alphat*Vt(7))*( (2*pi*K*r(7)*L(7))/h(7) *(1/2*(pb(7)+pb(8)) -pt7) -M*Vt(7));
      dpt8=1/(alphat*Vt(8))*( (2*pi*K*r(8)*L(8))/h(8) *(1/2*(pb(8)+pb(9)) -pt8) -M*Vt(8));
      dpt9=1/(alphat*Vt(9))*( (2*pi*K*r(9)*L(9))/h(9) *(1/2*(pb(9)+pb(10)) -pt9) -M*Vt(9));
      dpt10=1/(alphat*Vt(10))*( (2*pi*K*r(10)*L(10))/h(10) *(1/2*(pb(10)+pb(11)) -pt10) -M*Vt(10));
      dpt11=1/(alphat*Vt(11))*( (2*pi*K*r(11)*L(11))/h(11) *(1/2*(pb(11)+pb(12)) -pt11) -M*Vt(11));
      dpt12=1/(alphat*Vt(12))*( (2*pi*K*r(12)*L(12))/h(12) *(1/2*(pb(12)+pb(13)) -pt12) -M*Vt(12));
      dpt13=1/(alphat*Vt(13))*( (2*pi*K*r(13)*L(13))/h(13) *(1/2*(pb(13)+pb(14)) -pt13) -M*Vt(13));
      pt_tot=[pt1;pt2;pt3;pt4;pt5;pt6;pt7;pt8;pt9;pt10;pt11;pt12;pt13];
      dy=[dpt1;dpt2;dpt3;dpt4;dpt5;dpt6;dpt7;dpt8;dpt9;dpt10;dpt11;dpt12;dpt13];
      end
      t_start=0;
      t=t_start;
      y=cond;
      while idx_seg< length(t_seg)
          idx_seg=idx_seg+1;
          t_end=t_seg(idx_seg);    
      [t_sol,y_sol]=ode15s(@(t,y)f1_v1,[t_start, t_end],y(end,:));
      t = [t; t_sol(2 : end)];
      y = [y; y_sol(2 : end, :)];
      t_start = t_end;
      end
      for i=1:1:14
          if i==1
              pb=Pin(idx_seg);
          else
          pb(i)=pb(i-1)-pdrop(i);
          end
      end
      diffp=diff(pb)*(-1);
      pb_s=[pb(1)+pb(2);pb(2)+pb(3);pb(3)+pb(4);pb(4)+pb(5);pb(5)+pb(6);pb(6)+pb(7);pb(7)+pb(8);pb(8)+pb(9); pb(9)+pb(10);pb(10)+pb(11);pb(11)+pb(12);pb(12)+pb(13);pb(13)+pb(14)];
      for z=1:1:14
          S(z)=(((pb(z)^3+150*pb(z))^(-1) *23400)+1)^(-1);
      end
      deltaS=diff(S)*(-1);
      for j=1:1:13
          kin=v;
          compl(j)=((3*pi*L(j)*r(j)^3)/(2*Ey*h(j)) )*10^-3; %vessel compliance   (ElBouri2018) [ml/mmHg]   
          Vb(j)=(compl(j)/2)*pb_s(j); %[ml]
          q(j)=diffp(j)/R(j);
          Vt(j)= chb*H*q(j)*deltaS(j)/M;
      end
      for m=1:1:13
                    pt_weight(m)=y_sol(m)*Vt(m);
                 end
                 Vttot=Vt.*n;
      Vt_sum=sum(Vttot);
      ptot=sum(1/Vt_sum * (pt_weight));
      end

These are the initial conditions and times I run it with:

cond=[51.2112  ; 63.8766  ; 60.7979  ; 49.0010 ;  35.3767 ;  28.5718  ; 33.7930 ;  31.1300 ;  30.6594  ; 29.9741 ;  30.2541  ; 29.6828  ; 28.9798 ]; 
 [t, y] = f2_v4_21_08_18(cond, [0, 10, 100], [60, 70, 60]);
plot(t, y);

Thanks in advance!

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Answer 1

Torsten 2018-8-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/415784-matlab-ode15s-change-parameter-value-at-specific-time-during-solution#answer_333675

t_start = 0 und t_seg(1) = 0.

In the first call to ODE15S, you consequently try to integrate from t_start=0 to t_end=0 which is not accepted by the integrator.

Best wishes

Torsten.

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gorilla3 2018-8-22

在 MATLAB Online 中打开

Thanks! I now get the following error:

Index exceeds matrix dimensions.
Error in f2_v4_21_08_18/f1_v1 (line 32)
pt1=y(1); pt2=y(2); pt3=y(3); pt4=y(4);  pt5=y(5);  pt6=y(6);  pt7=y(7);  pt8=y(8);  pt9=y(9);  pt10=y(10);  pt11=y(11);  pt12=y(12);  pt13=y(13);

I don't know why since I have 13 initial conditions and then 13 equations... Could you please clarify this?

Torsten 2018-8-22

cond is 13x1, thus y is 13x1 at the start. Consequently y(end,:) is a scalar, not a vector of length 13.

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Matlab ode15s change parameter value at specific time during solution

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Matlab ode15s change parameter value at specific time during solution

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