how to convert matlab file in octave file

[James Sherman Jr.]

Not to sound obvious, but have you tried running this script in Octave?  If
so, what errors do you get?

On Fri, Jul 3, 2009 at 7:14 PM, Carletto Rossi <nuovodna at gmail.com> wrote:

> Hi guys. I would to convert this Matlab script in an Octave file:
>
> N = 4; %number of particles
> n = 1000; %size of cell
> iteration = 500; %times of measurement
> step = 20; %number of steps per-iteration
> T = 1.0; %temperature
> K = 1.0; %Bolztmann constant
> x = zeros(N,1);
> y = zeros(N,1);
> p = 1;
> too_near = 0;
> % ###################### initiation ############################
> while(p <= N)
>    %generate trial position
>    x_trial = rand*n;
>    y_trial = rand*n;
>    for q = 1:p
>        d = sqrt( (x_trial-x(q))^2 + (y_trial-y(q))^2 );
>        if(d <= 1.0) %the new position is too "near"
>            too_near = 1;
>            break; %there's no need to continue the loop
>        else
>            too_near = 0;
>        end
>
>     end
>     if(too_near == 0) %the new position is "far", accept it
>         x(p) = x_trial;
>         y(p) = y_trial;
>         p = p+1; %step increment
>     end
> end
> % ######################### metropolis #############################
> for k=1:iteration
>     W_initial = calculate_potential(N,x,y);
>     for j=1:step %how many steps per-iteration
>         for i=1:N     %for all particles
>            %step range between [-0.5,0.5]
>            trial_x = rand-0.5;
>            trial_y = rand-0.5;
>            %save the old values lest the step is not accepted
>            x_temp = x(i);
>            y_temp = y(i);
>            %trial step, bounded by the periodic boundary condition
>            x(i) = x(i) + trial_x;
>            if (x(i) > n)
>                x(i) = x(i) - n;
>            elseif (x(i) < 0.0)
>                x(i) = n + x(i);
>            end
>            y(i) = y(i) + trial_y;
>            if (y(i) > n)
>                y(i) = y(i) - n;
>            elseif (y(i) < 0.0)
>                y(i) = n + y(i);
>            end
>
>             W_final = calculate_potential(N,x,y);
>             if( (W_final-W_initial) < 0.0 ) %move is accepted
>                 W_initial = W_final;
>             else %apply metropolis criterion
>                 if (rand < exp(W_initial-W_final)/(K*T))
>                     W_initial = W_final;
>                 else %move is not accepted, return to initial position
>                     x(i) = x_temp;
>                     y(i) = y_temp;
>                 end
>             end
>         end
>     end
>     scatter(x,y,3,[0 0 1], 'filled') %plot 2D scatter-graph
>     F(k) = getframe; %capture every plot
> end
> save simulation.mat F;
> movie2avi(F, 'simulation.avi');
> % ################# calculate potential ###################
> function E = calculate_potential(N,x,y)
>
>     E = 0;
>
>      for i=1:N %for all particles
>          for j=(i+1):N %compute the potential of j with respect to i
>              d = sqrt( (x(j)-x(i))^2 + (y(j)-y(i))^2);
>              U = d^(-12) - d^(-6); %Lennard-Jones potential
>              E = E + U;
>          end
>      end
>
> Thanks in advance
>
>
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>
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