Re: bfgsmin help

[Dek1024]

Dek1024 wrote
> I tried executing 'bfgsmin' to fit a linear curve to the specified data
> set.
> <http://octave.1599824.n4.nabble.com/file/t372910/trainedmodel.png>  
> 
> In the above image the blue line is the curve obtained with gradient
> descent.
> But when trying to execute the same using bfgsmin to check how it works,
> it
> gives me the following error.
> 
> *EXAMPLE 4: Ordinary BFGS, using numeric gradient
> error: horizontal dimensions mismatch (1x1 vs 2x1)
> warning: __bfgsmin_obj: objective function could not be evaluated -
> setting
> to DBL_MAX
> warning: called from
>     bfgsmin at line 129 column 35
>     BFGS at line 12 column 30
> error: horizontal dimensions mismatch (1x1 vs 2x1)
> error: called from
>     objective2 at line 6 column 23
>     bfgsmin at line 129 column 35
>     BFGS at line 12 column 30
> *
> 
> *Here is the code for bfgsmin*
> 
> /data = load('ex1data1.txt');
> y = data(:,2);
> m = length(y);
> X = [ ones(m,1), data(:,2)];
> dim = 1;
> theta = zeros(dim+1,1);  # starting values
> location = (0:dim)/dim; # true values
> location = location';
> printf("EXAMPLE 4: Ordinary BFGS, using numeric gradient\n");
> t=cputime();
> control = {100;2;1;1};  
> [theta, obj_value, convergence] = bfgsmin("objective2",
> {theta,location,X,y}, control);
> fflush(1);
> t4 = cputime() - t;
> conv = norm(theta-location, 'inf');
> test4 = conv < 1e-5;
> printf("EXAMPLE 4: Ordinary BFGS, using numeric gradient\n");
> if test4
>       printf("Success!! :-)\n");
> else
>       printf("Failure?! :-(\n");
> endif
> printf("Elapsed time = %f\n\n\n\n",t4);/
> 
> *Here is the code for objective funcion*
> 
> 
> /function [obj_value, gradient] = objective2(theta,location,X,y)
>   m = length(y);
>   x = theta - location + ones(rows(theta),1); # move minimizer to
> "location"
>   [obj_value, gradient] = [((1/(2*m)) * sum(((X * x) - y).^2)),
> ((1/m)*((((X*theta)-y)'*X)'))]
> endfunction/
> 
> *I tried executing the same without analytical gradient, but obtained a
> similar error.(Given Below)*
> 
> /obj_value =  26.734
> warning: __bfgsmin_obj: objective function could not be evaluated -
> setting
> to DBL_MAX
> warning: called from
>     bfgsmin at line 129 column 35
>     BFGS at line 12 column 30
> obj_value =  26.734
> obj_value =  26.734
> warning: __bfgsmin_obj: objective function could not be evaluated -
> setting
> to DBL_MAX
> warning: called from
>     bfgsmin at line 129 column 35
>     BFGS at line 12 column 30
> error: __numgradient: objective function failed, can't compute numeric
> gradient
> error: called from
>     bfgsmin at line 129 column 35
>     BFGS at line 12 column 30/
> 
> The dataset is a textfile(ex1data1.txt) consisting of a 97 * 2 matrix with
> the first row containing *population* and second row containing *profit *. 
> 
> I took help from  this page
> &lt;https://sourceforge.net/p/octave/optim/ci/03e17f135cbe8a154dd01a341b72f454636f507f/tree/inst/bfgsmin_example.m#l155&gt;
>   
> for executing the code.
> 
> I am unable to debug the code.(Don't know why the objective function
> implementation fails)
> 
> Here is the text file  ex1data1.txt
> &lt;http://octave.1599824.n4.nabble.com/file/t372910/ex1data1.txt&gt;  .
> 
> 
> 
> 
> 
> 
> 
> 
> --
> Sent from:
> http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html

Here is the trimmed version of the same problem:

That post was very exhaustive.


*I tried executing 'bfgsmin' to fit a linear curve to a data set, the
following error occured:*


/warning: __bfgsmin_obj: objective function could not be evaluated - setting
to DBL_MAX
error: horizontal dimensions mismatch (1x1 vs 2x1)
/

*I tried executing the same without analytical gradient, but obtained a
similar error.(Given Below)
*

/warning: __bfgsmin_obj: objective function could not be evaluated - setting
to DBL_MAX

warning: __bfgsmin_obj: objective function could not be evaluated - setting
to DBL_MAX
warning: called from
  
error: __numgradient: objective function failed, can't compute numeric
gradient/



*I am unable to debug the code.(Don't know why the objective function
implementation fails)*
.



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Sent from: http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html