For loop returns all values as NaN

When I run this for loop, all the values are returned as NaN. I was wondering if anyone could help me find where I went wrong.

for i=1:N
     Pao(i)=(Vao(i)-Vao0)/Cao;
     Pla(i)=(Vla(i)-Vla0)/Cla;
     Psm(i)=(Vsm(i)-Vsm0)/Csm;
     Pve(i)=(Vve(i)-Vve0)/Cve;
     Phe(i)=(Vhe(i)-Vhe0)/Che(i); 
     Pca(i)=(Vca(i)-Vca0)/Cca;
     if Phe(i)>Pao(i); Q1(i)=(Phe(i)-Pao(i))/Rha;
     else Q1(i)=0;
     end
     Q3(i)=(Pao(i)-Pla(i))/Ral;
     Q2(i)=Q1(i)-Q3(i);
     Vao(i+1)=Vao(i)+Q2(i)*dt;
     Q5(i)=(Pla(i)-Psm(i))/Rls;
     Q4(i)=Q3(i)-Q5(i);
     Vla(i+1)=Vla(i)+Q4(i)*dt;
     Q7(i)=(Psm(i)-Pca(i))/Rsc;
     Q6(i)=Q5(i)-Q7(i);
     Vsm(i+1)=Vsm(i)+Q6(i)*dt;
     Q9(i)=(Pca(i)-Pve(i))/Rcv;
     Q8(i)=Q7(i)-Q9(i);
     Vca(i+1)=Vca(i)+Q8(i)*dt;
     if Pve(i)>Phe(i); Q11(i)=(Pve(i)-Phe(i))/Rvh;
     else Q11(i)=0;
     end
     Q10(i)=Q9(i)-Q11(i);
     Vve(i+1)=Vve(i)+Q10(i)*dt;
     Q12(i)=Q11(i)-Q1(i);
     Vhe(i+1)=Vhe(i)+Q12(i)*dt;  
    end

And this is my parameter file

%Volumes and residual volumes in L:
Vhe=.1; Vhe0=0; 
Vao=.15; Vao0=.085;
Vla=.35; Vla0=.17;
Vsm=.05; Vsm0=.02;
Vca=.3; Vca0=.06;
Vve=3.25; Vve0=.65;

%Resistances in (mmHg*s)/L:
Rha=60.08; %
Ral=12.0;
Rls=380.4;
Rsc=241.2;
Rcv=279.6;
Rvh=26.90;

%Compliances in L/mmHg:
Cao=.0007;
Cla=.002;
Csm=.0005;
Cca=.006;
Cve=.156;
Chs=.0006; 
Chd=.01; 

s=30;
d=60;
N=800;
dt=1;
n=10;

Answer 1

[Star Strider]

A NaN result usually indicates an attempt to do a 0/0, Inf/Inf or a calculation involving NaN.

There must be more to your code than you’re telling us. When I run this:

Vao=.15; Vao0=.085;
Cao=.0007;

Pao(1)=(Vao(1)-Vao0)/Cao;
Pao(2)=(Vao(2)-Vao0)/Cao;

I get:

Index exceeds matrix dimensions.

Error in ... (line ...)
Pao(2)=(Vao(2)-Vao0)/Cao;