vector size conflict?

[tessaract87]

Hi all,

I'm working on implementing a model using differential equations.  The main
function of the model looks like this:

function V=f(x,t)
BDR=0.016;
SPC=5.8*10^-3;
SC=0.01377;
SHC=0.025;
V=zeros(6,1);

V(1)=BDR*(V(2)+V(3))-(SRB(V(1),V(4))*V(2)+PS(V(1),V(6))*V(3));
V(2)=SRB(V(1),V(4))*V(2)-(BDR)*V(2);
V(3)=PS(V(1),V(6))*V(3)-BDR*V(3);
V(4)=SPC*V(5)-SRB(V(1),V(4))*SC*V(2)*V(5);
V(5)=PS(V(1),V(6))*SHC*V(3)*V(6)-SPC*V(5);
V(6)=SRB(V(1),V(4))*SC*V(2)*V(4)-PS(V(1),V(6))*SHC*V(2)*x(6);
endfunction

With SRB and PS being two functions as follows:

function[answer]=PS(i,w)
V=0.528;
KmC=0.22;
KmP=0.0002;
KmN=0.02;
KmSH=3;
PC=106;
PN=16;
answer=((V*i)/(KmP+i))*(i/((KmN/PN)+i))*(i/((KmC/PC)+i))*(w/(KmSH+w));
return
endfunction

and

function [answer]=SRB(i,y)
V=0.528;
KmC=0.22;
KmP=0.0002;
KmN=0.02;
KmS=3;
PN=16;
PC=106;
KmSH=3;
SRB=((V*i)/(KmP+i))*(i/((KmN/PN)+i))*(i/((KmC/PC)+i))*(y/(KmS+y));
return
endfunction

both of which should return scalar values.  

However, when I attempt to run the file, I get the following error:

warning: SRB: some elements in list of return values are undefined
error: Venus: A(I) = X: X must have the same size as I
error: called from:
error:   /home/tessa/Venus.m at line 16, column 5

Clearly, there's a conflict with the size of the vectors- but I can't figure
out where.  Each equation in the main function should return a scalar value,
and this type of formatting has worked in other, example differential
equations I've looked at.  What am I doing wrong?

Thanks!




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