Model is unsuitably constrained (i.e. there were still some variables left to be computed, and some unusable equations left over).
At the time of the error, the following variables were found:
 * Undefined: v in component gating_Icat
 * Undefined: x_cat_inf_act in component gating_Icat
 * Undefined: x_cat_inf_inact in component gating_Icat
 * Undefined: tau_cat_act in component gating_Icat
 * Undefined: tau_cat_inact in component gating_Icat
The following equations couldn't be used:
 * Equation with no id on the apply or math element.
 * Equation with no id on the apply or math element.
 * Equation with no id on the apply or math element.
 * Equation with no id on the apply or math element.