Function requires more inputs

Hi! I am trying to work the following code, but it keeps saying that I need more inputs:

function r = rxnrate(F)
global k Keq 
Fa=F(1);
Fb=F(2);
Fc=F(3);
Fd=F(4);
f=33.3;
P=1;
Pa=(Fa/f)*P;
Pb=(Fb/f)*P;
Pc=(Fc/f)*P;
Pd=(Fd/f)*P;
r(1)=k*((Pa*Pb)-(Pc*Pd/Keq));
r(2)=k*((Pa*Pb)-(Pc*Pd/Keq));
r(3)=k*((Pa*Pb)-(Pc*Pd/Keq));
r(4)=k*((Pa*Pb)-(Pc*Pd/Keq));
r=r';
end

Answer 1

[Walter Roberson]

To run that code, you need to have first executed some code that used

global k Keq

and then assigned values to k and Keq.

That having been done once, you need to invoke the routine passing in data, such as

   ftest = randn(1,4);
   result = rxnrate(ftest);

It is not possible to invoke the code by simply typing the name of the function, or by simply pressing the green Run button while you are in the editor on this function. Even if you have defined F in your current workspace, MATLAB will not look for an F in the hierarchy if you try to invoke rxnrate without passing in anything.