Acceleration methods for shielding current analysis in cracked superconducting film

Two methods are proposed for accelerating the shielding current analysis in a cracked superconducting film: fast matrix-vector multiplication by the H-matrix method and variable reduction by the QR factorization. Both methods are implemented in a numerical code for calculating the time evolution of the shielding current density. By using the code, the performance of both methods are numerically investigated. The results of computations show that, when combined with the H-matrix method, the variable reduction shows a remarkable speedup effect.