refactoring solver_cese.py: abandon variable ia and useless delta_precision
refactoring solver_cese.py: abandon variable ia and useless delta_precision

yungyuc/solvcon,solvcon/solvcon,yungyuc/solvcon,yungyuc/solvcon,yungyuc/solvcon,solvcon/solvcon,yungyuc/solvcon,solvcon/solvcon,solvcon/solvcon,yungyuc/solvcon,solvcon/solvcon,solvcon/solvcon