Algorithm 1 Regularization Solver Guided Fast Iterative Shrinkage Threshold Algorithm (RS-FISTA)

INPUT: Sensitivity matrix A, voltage y; parameters: denoising parameter α = 10−9, relative tolerance Epsilon = 10−5, maximum iterations Itermax. Setting the initial value t(1) = 1, k = 1, error = 0 Calculate the regular resolution as the initial value of the algorithm x(0), z(1) = x(0) Calculate the step size μ in the RS-FISTA method, $\mu =\frac{1}{L}$ If it does not reach the convergence criterion or the error is greater than the relative tolerance, (1) Calculate x(k), $x^{(k)}={{\rm T}}_{\alpha }[{\mathrm{z}}^{(k)}-\mu A^T(A{z}^{(k)}-y)]$ (2) Update parameter t(k + 1) of the RS-FISTA method, $t^{(k+1)}=\frac{1+\sqrt{1+4\times {(t^{(k)})}^2}}{2}$ (3) Calculate ${\mathrm{z}}^{(k+1)}$, ${\mathrm{z}}^{(k+1)}=x^{(k)}+\frac{t^{(k)}-1}{t^{(k+1)}}(x^{(k)}-x^{(k-1)})$ (4) Calculate error, $error=|y-A{x}^{(k)}|$ (5) $k=k+1$     end OUTPUT: The calculated conductivity matrix x(k), the error between the actual voltage and the estimated voltage error.