We present a least-squares mixed finite element approximation ofan elliptic problem with degenerate coefficients, arising in the study of the electronmagnetic field in a resonant structure with cylindrical symmetry. Optimal error estimates are developed, especially in the case of differing polynomial degrees for the primary solution approximation uh and the flux approximation σh.
退化系数 椭圆问题 最小二乘混合元 收敛性