Direct solutions of 3-D magnetotelluric fields using edge-based finite element

This paper utilizes the 3-array variation of the compressed sparse row (CSR) format to store upper triangular elements of coefficient matrix, and applies the Intel MKL PARDISO solver to solve large sparse linear systems of equations, when calculating the 3-D magnetotelluric (MT) fields using edge-based finite element (FE). By default, Intel MKL PARDISO stores matrices in RAM, namely in-core (IC) mode, however, it is quite memory consumption. One can specify that Intel MKL PARDISO stores matrices on disk, it is referred to as out-of-core (OOC) mode. But the OOC mode consumes longer time than the IC mode. We compare both time and memory consumption of IC and OOC mode via COMMEMI 3D-1A and 3D-2A models. As shown in the examples, the OOC mode can solve very large problems since the amount of main memory required is significantly reduced, in the acceptable computing time, which makes frequency loop parallelization of 3-D MT modeling possible on a small memory PC.