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/* The Analogy between Thermal and Electrostatic Equations */
Similarly, one can establish an analogy between the heat flux <b>q(r)</b> and the static electric field <b>E(r)</b>:
<math> q = -k\nabla T(\mathbf{r}) \quad \leftrightarrow \quad \mathbf{E(r)} = - \nabla \Phi(\mathbf{r})</math>
