Re: vector size conflict?

[Juan Pablo Carbajal]

On Thu, Nov 6, 2014 at 9:10 PM, tessaract87 <address@hidden> wrote:
> 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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>
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In the last line of your SRB function you return SRB instead of answer!

Also check that for some of your functions the arguments are always
zero...which doesn't seem to make much sense.