New Preconditioners for Nonsymmetric Saddle Point Systems with Singular (1,1) Block

Table 1

Iteration time and iteration numbers of GMRES of block triangular preconditioner 𝓐 for different 𝑘 with 𝑚+𝑛=1200.

Nullity	k	0.5	1	1.5	2	2.5
3m/4	Time	102.9954	126.6284	63.4525	36.4118	54.9560
	Iter	16	18	9	5	8
m	Time	2.8677	2.8821	3.0962	2.3289	3.0844
	Iter	1	1	1	1	1