Error in ezplot while plotting complicated symbolic function

Hi,

I'm plotting a complicated symbolic function using ezplot and I get the following error. I was wondering whether this a bug?

??? Undefined function or method 'isfinite' for input arguments of type 'sym'.

Error in ==> ezplot>ezimplicit at 264 uu = sort(u(isfinite(u)));

Error in ==> ezplot at 155 hp = ezimplicit(cax, f{1}, vars, labels, args{:});

Error in ==> mass_spring_passive_dynamics at 14 ezplot(fx)

Regards,

Priyanshu