求解器Krylov、Spar、CG_ILU、Mumps之间的区别如下：
Krylov 求解器：利用阻抗Z(春风十里简谱) 与频率 f()的结构形式
Z(火影忍者女) ：二阶函数
f() = f0+f1： 机修工作总结线性函数
直接求解4个频率，Krylov 子空间重构，显著减少CPU计算时间，对内存需求不变，精度没有影响，对模态提取与多孔介质不适用。黑胡椒意大利面Krylov求解器需要与子求解器MUMPS或SPARSE连用，适用多频率点计算。例如计算范围10-1000Hz，分析步孕妇汤1Hz和2Hz时时间几乎一致，但用其它求解器时间会存在倍数关系。ACTRAN_12.2_Urs_Guide_Vol1(6.2.7)
局限：不能用于DIFFUSE_FIELD和TURBULENT分析；不能用于管道模态声源分析；不能用于来自外部求解器载荷如BC_MESH和Aero-acoustic sources；关公赴会歇后语下一句
对比语言学
SPARSE and MUMPS求解器：直接求解，快速，高效，利用稀疏矩阵的特点，大规模问题的求解。SPARSE是Actran默认求解器，但MUMPS比SPARSE性能好大多数情况下取代它。
MUMPS (Multifrontal Massively Parallel Solver)，需要内存少，MUMPS适用所有应用场合，特别适用对集群并行求解很有优势。
The RHS_BLOCK_SIZE option is a common option for all the direct solvers like SPARSE and MUMPS (not supported with iterative solvers like CG_ILU and KRYLOV), and allows to handle multiple right-hand-sides by blocks during the backtransformation step. This allows to reduce the memory ud during the factorization and the back-transformation when computing a high number of loadcas.The conquence is an increa of the time required by the back-transformation.The default value of this parameter is 0, which corresponds to no partitioning of the right hand side.
The MEMORY_RELAXATION corresponds to a percentage increa in the estimated working space (default value 0.2). Decreasing this parameter allows consuming less memory, but a minimal overestimation should always be provided. This parameter should be incread when extra memory usage is encountered (for instance due to additional numerical pivoting).
The ORDERING parameters lects the ordering method ud inside the solver. Four ordering methods are available:
CG_ILU求解器：迭代求解器，使用频率不多，优势对内存要求更低，计算时间也少，但是迭代不容易收敛。迭代求解器适用与有限元与无限元场合；模态组件；多孔材料，但不适用声振耦合计算。
The advantage of this method is that the memory cost remains low. Another advantage is that the computational time may be low. A drawback of this method is that the iterative process may not converge
The iterative method works best with:
_ acoustic finite and infinite elements;
_ modal components;叶儿粑
_ porous materials.
The iterative method does not work for structural nor vibro-acoustic models, i.e.with DSHELL elements, SHELL elements or SOLID elements.
