1. The problem statement, all variables and given/known data There are six coils(Multi-layer circular solenoid).loops for the coaxial loops. I konw all their dimensions,turns,layers. 2. Relevant equations Because I need very accurate inductance,so I use GROVER's fomulate for self-inductance and maxwells' for mutual inductance. I write a program,but it is very complicate,the cpu need several hours to give me a result. 3. The attempt at a solution Is there some way to optimal it? Or is there some efficient calculation techniques?