= Exponential memory from tensor relaxation
{title2=$A(t)=e^{-t/\tau}A(0)+\alpha\int_0^t e^{-(t-s)/\tau}\|Q(s)\|^{n-1}Q(s)^T\,ds$}
The <dissipation potential> $\Omega=\alpha\|Q\|^{n+1}/(n+1)-\operatorname{tr}(AQ)/\tau$, with the <Frobenius norm>, gives $\dot A+A/\tau=\alpha\|Q\|^{n-1}Q^T$. An <integrating factor> proves the displayed memory formula. For $n>0$, its nonlinear driving term is defined continuously as zero at $Q=0$. Mechanical dissipation is $\operatorname{tr}(Q\dot A)=\alpha\|Q\|^{n+1}-\operatorname{tr}(AQ)/\tau$, which must be nonnegative on thermodynamically admissible histories.
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