fzero help please I need value of y...the complete code is as follows

I wrote following code in matlab.

% declare global variables
global bcr vc locr rc rb wb
% define given parameters
bcr = 0.713; 
vc = 0.18; 
locr=0.092; 
rc = 0.056; 
rb = 0.008; 
wb = 1.19;

% compute the root of wc f(wc)=0.0 using fzer0 function
[y,fval,exitflag,output] = fzero('myfun_y',[0.008,0.056])

function file is as follows:

% function file to calculate value of y at which f(y) = 0.0 using fzero
function f = myfun_y(y)

% declare global variables
global locr rb vc rc wb bcr 

% define function f(y)
f1 = ((y-rb)/(locr*(locr-y)*(locr-rb)))+((1/locr^2)*log((y*(locr-rb))/(rb*(locr-y))));
f2 = (y*(locr-y))*((1.+vc)+(1.-vc^2)*(rc^2-y^2)/(rc^2+y^2));
f3 = wb*bcr;
f = f1*f2-f3;
end

*When I run, this code I got following message.

Error using fzero (line 233)
FZERO cannot continue because user supplied function_handle ==> myfun_y
 failed with the error below.

   Not enough input arguments.

Error in compute_y (line 22)
[y,fval,exitflag,output] = fzero('myfun_y',[0.008,0.056]) *

ANy idea, what is going on...I need value of y between 0.008 and 0.56...

*I am hating fzero now...it is giving me hard time.

Answer 1

[Walter Roberson]

Experiment with replacing

[y,fval,exitflag,output] = fzero('myfun_y',[0.008,0.056])

with

[y,fval,exitflag,output] = fzero(@myfun_y, [0.008,0.056])

[Nic]

Thanks walter....I tried with @myfun_y... exactly same error message...have you any idea why this is happening..

[Walter Roberson]

It is the log* that is the problem. Not enough input arguments to log.

[Nic]

Hi, I change log* ... and run the program... it is giving right value of y which is 0.008 when wb =0.0.... But when I change the value of wb to 1.0..I got following error message.... I need to solve this problem please help. thank you so much.

(when wb =1.0)** Error using fzero (line 274) The function values at the interval endpoints must differ in sign. Error in compute_y (line 23) [y,fval,exitflag,output] = fzero(@myfun_y,[0.008, 0.056])

• (when wb =0.0)** y =

    0.0080

fval =

     0

exitflag =

     1

output =

    intervaliterations: 0
            iterations: 0
             funcCount: 2
             algorithm: 'bisection, interpolation'
               message: 'Zero find terminated.'