Problem using Hessian function

Hi ,

I am trying to calculate the hessian of the following function :

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function logl = tryseven(p, xdata, ydata)

a = p(1);

b = p(2);

f = p(3);

g = p(4);

h = size(xdata,2)*log(a);

i = size(xdata,2)*log(b);

j = (b-1)*(log(ydata - f - g*xdata));

k = a*((ydata - f - g*xdata).^b);

logl = [-sum(j(:)) + sum(k(:) -h -i)];

end

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I run the following command , by providing the point at which Hessian has to be calculated:

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   p(1) =  0.5272;

   p(2) =  1.2401;

   p(3) = -0.5815;

   p(4) =  14.2491;

[hess,err]=hessian(@(p) tryseven(p, xdata, ydata))

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But I am getting an error "Not enough input arguments."

Can somebody please tell me what error I have committed? I have attached my data.

Regards,

Prachi

Answer 1

[Walter Roberson]

Are you trying to use Symbolic Toolbox hessian() ? If so then it requires a symbolic function or symbolic expression first argument, an requires a vector of symbolic names as a second argument.

If you are trying to use This File Exchange Contribution then a scalar function first argument is fine, but the second argument needs to be the location to evaluate the Hessian at.