# Using multiple functions in matlab Errors

1. May 12, 2012

### adeeyo

Dear All,

Please I need your assistance in solving this matlab problem. I will be glad to hear from you as early as possible. Thanks for your anticipated help

I have three functions

First one

function f_PR_W=newtonphasemolefraction1(W_PR, z,C,K_PR )
f_PR=0;
for c=1:C

f_PR_W=f_PR+z(c).*(1-K_PR(c))./(1+W_PR.*(K_PR(c)-1));
end

Another function

function fdot_PR_W=newtonphasemolefraction2(W_PR, z,C,K_PR )
fdot_PR=0;

for c=1:C
fdot_PR_W=fdot_PR+z(c).*(K_PR(c)-1).^2/(W_PR.*(K_PR(c)-1)+1).^2;

end

The third function

function [W_PR,err,k,f_PR_W]=newton1(newtonphasemolefraction1,newtonphasemolef raction2,W_PR,Tol_W_PR,Tol_f_PR,maxIter)

for k=1:maxIter
p1=W_PR-newtonphasemolefraction1(W_PR)/newtonphasemolefraction2(W_PR);
err=abs(p1-W_PR);
relerr=2*err/(abs(p1)+Tol_W_PR);
W_PR=p1;
f_PR_W=newtonphasemolefraction1(W_PR);
if (err<Tol_W_PR)|(relerr<Tol_W_PR)|(abs(f_PR_W)<Tol_ f_PR),break,end
end

I call the three functions using

[W_PR,err,k,f_PR_W]=newton1(newtonphasemolefraction1,newtonphasemolef raction2,W_PR,Tol_W_PR,Tol_f_PR,maxIter)

I received the following error

"Error using newtonphasemolefraction1 (line 3)
Not enough input arguments."

And all input arguments were defined: K_PR=[0.01546,0.5,1.432],W_PR=0.25,Tol_W_PR=10^-6, Tol_f_PR=10^-10, maxIter=100, z=[0.1 0.3 0.6],C=3

Please assist.

Best regards,
adeeyo

2. May 13, 2012

### Stephen Tashi

I don't know Matlab, but in most computer languages your would have to write something like:

[W_PR,err,k,f_PR_W]=newton1(newtonphasemolefraction1(a,b,c,d),
newtonphasemolefraction2(e,f,g,h),.. etc.

because you can't assume the compiler knows what arguments you want to pass to the functions newtonphasemolefraction1 and newtonphasemolefraction2 if you don't tell it. It looks like the compiler is objecting that you didn't supply any arguments to those functions.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook