error: Index exceeds matrix dimensions.

%This begins the force analysis
for turn=['a','b','c','d','e','f','g']
    r.(turn).r3=.331;
    r.(turn).force=r.(turn).force(:,2);
    r.(turn).v=length(r.(turn).force);
    r.(turn).justtime=r.(turn).justtime(1:r.(turn).v);
    r.(turn).justangle=r.(turn).justangle(1:r.(turn).v);
    r.(turn).sinangle=sin(r.(turn).justangle);
    r.(turn).nettorque=(r.(turn).r3)*(r.(turn).sinangle).*(r.(turn).force);
    for b=1:(r.(turn).v);
        r.(turn).deltatorque(b)=r.(turn).nettorque(b+1)-r.(turn).nettorque(b);
    end
    r.(turn).deltatorque=r.(turn).deltatorque.';
    r.(turn).network=(r.(turn).nettorque(1:r.(turn).v)).*(r.(turn).deltatheta(1:r.(turn).v));
    r.(turn).deltapotential=(r.(turn).nettorque).*(r.(turn).justangle);
    r.(turn).gravity=(9.81*(r.(turn).m))*(r.(turn).deltatheta);
    r.(turn).withoutgravity=(r.(turn).deltapotential(1:r.(turn).v))-(r.(turn).gravity(1:r.(turn).v));
    r.(turn).totalwork=sum(r.(turn).withoutgravity);
    fprintf('The Total Work is %f\n',r.(turn).totalwork)
end

[per isakson]

It's difficult to spot the cause of the error by inspection. The problem might even be with the input data rather than this code.