integrating in a for loop

Dear All,

I have written a for loop to solve two simultaneous equations (using fsolve function)to give me x(1) and x(2). Using these values , I compute various functions of these and of calibrated parameters.

One such function requires me to integrate a function of x(1) involing log normal pdf and cdf. I tried using the trapz and quad command but it always gave me errors.

I coded as gridzi=linspace(x(1)*0.0001,zfstar-0.0001,1000);

zicurl=trapz(gridzi,((gridzi.^(teata-1)).*(lognpdf(gridzi,mue,sd)./(1-(logncdf(x(1),mue,sd))))));% i need to find this integral

but it always gave an error

??? Error using ==> mpower Inputs must be a scalar and a square matrix.

Error in ==> model1lognormal at 27 zicurl=trapz(gridzi,((gridzi^(teata-1))*(lognpdf(gridzi,mue,sd)/(1-(logncdf(x(1),mue,sd)))))); % i need to find this integral

Error in ==> fsolve at 254 fuser = feval(funfcn{3},x,varargin{:});

Error in ==> runmodel1lognormalplot at 56 [x,fval,exitflag,output]=fsolve(@model1lognormal,x0plus,options,tariff);

Caused by: Failure in initial user-supplied objective function evaluation. FSOLVE cannot continue.

Please suggest how I should solve this. I urgently need to do this for my thesisi

Answer 1

[Jan]

The code you have posted differs from the one shown in the error message:

The uses ".^" with dot:

zicurl=trapz(gridzi,((gridzi.^(teata-1)).*(lognpdf(gridzi,mue,sd)./(1-(logncdf(x(1),mue,sd))))));

But in the error message the operator is "^":

 Error in ==> model1lognormal at 27 zicurl=trapz(gridzi,((gridzi^(teata-1)) * (lognpdf(gridzi,mue,sd) / (1-(logncdf(x(1),mue,sd))))));

Perhaps you've modified the function but did not save it?

[mk612]

ok, I will try again.

Also, should I put . before every mathematical operation ?

for example .* ./

Thanks

[Sean de Wolski]

Probably. Unless you want to do a matrix multiplication/division.

[mk612]

I added . before every mathematical operation.

However now I get another error?

??? Error using ==> lognpdf at 41

Non-scalar arguments must match in size.

Error in ==> model1lognormal at 27

zicurl=trapz(gridzi,((gridzi.^(teata-1)).*(lognpdf(gridzi,mue,sd)./(1-(logncdf(x(1),mue,sd))))));

% i need to find this integral

Error in ==> fsolve at 254

fuser = feval(funfcn{3},x,varargin{:});

Error in ==> runmodel1lognormalplot at 56

[x,fval,exitflag,output]=fsolve(@model1lognormal,x0plus,options,tariff);

pls suggest what I should do?

Answer 2

[Sean de Wolski]

You probably want to do an element-by-element power (x.^blah). You're trying to do a matrix power, hence the error in mpower.

The solution is simple, add a '.' in front of every '^'.

note the difference between

1.^ones(2)

and

1^ones(2)

[mk612]

Hi Sean,

I tried doing this but I am still getting the same error. Could you suggest something else.

Thanks

Mahima