Abstract
In this article, we study the constrained matrix approximation problem in the Frobenius norm by using the core inverse:
where
1 Introduction
Let
Let
Let
The core inverse of
Recently, the relevant conclusions of the core inverse are very rich. In [7,8,9,10], generalizations of core inverse are introduced, for example, the core-EP inverse and the weak group inverse. In [11,12,13,14,15], their algebraic properties and calculating methods are studied. In [16,17], the studying of them is extended to some new fields, for example, ring and operator. Moreover, those inverses are used to study partial orders in [4,5,10,18,19].
Consider the following equation:
Let
where
It is well known that
When
where
2 Preliminaries
Lemma 2.1
[1] Let
Furthermore,
Lemma 2.2
[3] Let
Lemma 2.3
[3] Let
Lemma 2.5
[14] Let
where
3 Main results
3.1 Solution of (1.3)
Proof
From
Let the decomposition of M be as in (2.2). Denote
where
Since T is invertible, we have
3.2 Determinantal formulas
When
is called Cramer’s rule for solving (1.2). In [29], Ben-Israel gets a Cramer’s rule for obtaining the least-norm solution of the consistent linear system (1.2),
where U and V are of full column rank,
First of all, we give the following two lemmas to prepare for a Cramer’s rule for core inverse in Theorem 3.4.
Lemma 3.2
Let
Proof
Let M be as in (2.2), applying Lemma 2.2, we see that
Denote
Applying Lemmas 2.1, 2.3 and
Since
Since
Therefore, applying Lemma 2.1, (3.7) and (3.10), we gain
i.e., (3.5).□
In [28, Theorems 3.2 and 3.3], let
is invertible and the unique solution
where
Lemma 3.3
Let M and L be as in Lemma 3.2. Then,
is invertible and
Proof
Since
that is, G is invertible and
Based on Lemmas 3.2 and 3.3, we get a Cramer’s rule for the unique solution of (1.3).
Theorem 3.4
Let M and b be as in Lemma 3.2, and let L be as in Lemma 3.2. Then, (1.3) has the unique solution
where
Proof
Since G is invertible, applying Lemma 3.3, we get the unique solution
In the following theorem, we give a characterization of the core inverse and prepare for a Cramer’s rule for the core inverse in Theorem 3.6.
Theorem 3.5
Let M and L be as in Lemma 3.2. Then,
Proof
Since
and
Therefore,
Since
It follows that we get (3.14).□
Theorem 3.6
Let M and L be as in Lemma 3.2. Then, (1.3) has the unique solution
where
Proof
Applying Theorems 3.5 to 3.1, we have
that is,
In [30], Ji obtains the condensed determinantal expressions of
Theorem 3.7
Let M and L be defined as in (3.11). Then, the core inverse
where
3.3 Examples
In the following examples, we show that our results are effective.
Example 3.1
Let
By applying Theorem 3.1, we get the solution of (1.3) is
For
For
Example 3.2
Let
Then,
and
with
By applying Theorem 3.5, we get
For
by applying Theorem 3.7, we get
that is,
Acknowledgments
Hongxing Wang was supported partially by the Guangxi Natural Science Foundation (grant number 2018GXNSFAA138181), the Special Fund for Science and Technological Bases and Talents of Guangxi (grant number GUIKE AD19245148), the Xiangsihu Young Scholars Innovative Research Team of Guangxi University for Nationalities (grant number 2019RSCXSHQN03) and the Special Fund for Bagui Scholars of Guangxi (grant number 2016A17). Xiaoyan Zhang was supported partially by the National Natural Science Foundation of China (grant number 11361009) and High Level Innovation Teams and Distinguished Scholars in Guangxi Universities (grant number GUIJIAOREN201642HAO).
-
Conflict of interest: The authors report no potential conflict of interest.
References
[1] A. Ben-Israel and T. N. E. Greville, Generalized Inverses: Theory and Applications, 2nd edn, Springer-Verlag, New York, 2003.Search in Google Scholar
[2] D. S. Cvetković Ilić and Y. Wei, Algebraic Properties of Generalized Inverses, Springer, Singapore, 2017.10.1007/978-981-10-6349-7Search in Google Scholar
[3] G. Wang, Y. Wei, and S. Qiao, Generalized Inverses: Theory and Computations, 2nd edn, Springer, Singapore, 2018.10.1007/978-981-13-0146-9Search in Google Scholar
[4] O. M. Baksalary and G. Trenkler, Core inverse of matrices, Linear Multilinear Algebra 58 (2010), no. 5–6, 681–697, 10.1080/03081080902778222.Search in Google Scholar
[5] H. Wang and X. Liu, Characterizations of the core inverse and the core partial ordering, Linear Multilinear Algebra 63 (2015), no. 9, 1829–1836, 10.1080/03081087.2014.975702.Search in Google Scholar
[6] R. E. Cline, Inverses of rank invariant powers of a matrix, SIAM J. Numer. Anal. 5 (1968), 182–197, 10.1137/0705015.Search in Google Scholar
[7] S. B. Malik and N. Thome, On a new generalized inverse for matrices of an arbitrary index, Appl. Math. Comput. 226 (2014), 575–580, 10.1016/j.amc.2013.10.060.Search in Google Scholar
[8] O. M. Baksalary and G. Trenkler, On a generalized core inverse, Appl. Math. Comput. 236 (2014), 450–457, 10.1016/j.amc.2014.03.048.Search in Google Scholar
[9] K. Manjunatha Prasad and K. S. Mohana, Core-EP inverse, Linear Multilinear Algebra 62 (2014), no. 6, 792–802, 10.1080/03081087.2013.791690.Search in Google Scholar
[10] H. Wang and J. Chen, Weak group inverse, Open Math. 16 (2018), 1218–1232, 10.1515/math-2018-0100.Search in Google Scholar
[11] Ivan Kyrchei, Determinantal representations of the quaternion core inverse and its generalizations, Adv. Appl. Clifford Algebr. 29 (2019), 104, 10.1007/s00006-019-1024-6.Search in Google Scholar
[12] H. Ma, Optimal perturbation bounds for the core inverse, Appl. Math. Comput. 336 (2018), 176–181, 10.1016/j.amc.2018.04.059.Search in Google Scholar
[13] K. Manjunatha Prasad and M. D. Raj, Bordering method to compute core-EP inverse, Spec. Matrices 6 (2018), 193–200, 10.1515/spma-2018-0016.Search in Google Scholar
[14] Hongxing Wang, Core-EP decomposition and its applications, Linear Algebra Appl. 508 (2016), 289–300, 10.1016/j.laa.2016.08.008.Search in Google Scholar
[15] H. Wang, J. Chen, and G. Yan, Generalized Cayley-Hamilton theorem for core-EP inverse matrix and DMP inverse matrix, J. Southeast Univer. (Engl. Ed.) 1 (2018), no. 4, 135–138, 10.3969/j.issn.1003-7985.2018.01.019.Search in Google Scholar
[16] Y. Gao and J. Chen, Pseudo core inverses in rings with involution, Comm. Algebra 46 (2018), no. 1, 38–50, 10.1080/00927872.2016.1260729.Search in Google Scholar
[17] D. S. Rakić, N. Č. Dinčić, and D. S. Djordjević, Core inverse and core partial order of Hilbert space operators, Appl. Math. Comput. 244 (2014), 283–302, 10.1016/j.amc.2014.06.112.Search in Google Scholar
[18] I. Kyrchei, Determinantal representations of the core inverse and its generalizations with applications, J. Math. 2019 (2019), 1–13, 10.1155/2019/1631979.Search in Google Scholar
[19] H. Wang and X. Liu, A partial order on the set of complex matrices with index one, Linear Multilinear Algebra 66 (2018), no. 1, 206–216, 10.1080/03081087.2017.1292995.Search in Google Scholar
[20] S. L. Campbell and C. D. Meyer, Generalized Inverses of Linear Transformations, Society for Industrial and Applied Mathematics (SIAM), Philadelphia, 2009.10.1137/1.9780898719048Search in Google Scholar
[21] Y. Wei, Index splitting for the Drazin inverse and the singular linear system, Appl. Math. Comput. 95 (1998), no. 2–3, 115–124, 10.1016/S0096-3003(97)10098-4.Search in Google Scholar
[22] Y. Wei, A characterization for the W-weighted Drazin inverse and a Cramer rule for the W-weighted Drazin inverse solution, Appl. Math. Comput. 125 (2002), no. 2–3, 303–310, 10.1016/S0096-3003(00)00132-6.Search in Google Scholar
[23] Y. L. Chen, Representations and Cramer rules for the solution of a restricted matrix equation, Linear and Multilinear Algebra 35 (1993), no. 3–4, 339–354, 10.1080/03081089308818266.Search in Google Scholar
[24] K. Morikuni and M. Rozluŏzník, On GMRES for singular EP and GP systems, SIAM J. Matrix Anal. Appl. 39 (2018), no. 2, 1033–1048, 10.1137/17M1128216.Search in Google Scholar
[25] F. Toutounian and R. Buzhabadi, New methods for computing the Drazin-inverse solution of singular linear systems, Appl. Math. Comput. 294 (2017), 343–352, 10.1016/j.amc.2016.09.013.Search in Google Scholar
[26] G. Wang, A Cramer rule for finding the solution of a class of singular equations, Linear Algebra Appl. 116 (1989), 27–34, 10.1016/0024-3795(89)90395-9.Search in Google Scholar
[27] Y. Wei and H. Wu, Convergence properties of Krylov subspace methods for singular linear systems with arbitrary index, J. Comput. Appl. Math. 114 (2000), no. 2, 305–318, 10.1016/S0377-0427(99)90237-6.Search in Google Scholar
[28] H. Ma and T. Li, Characterizations and representations of the core inverse and its applications, Linear Multilinear Algebra (2019), 10.1080/03081087.2019.1588847.Search in Google Scholar
[29] A. Ben-Israel, A Cramer rule for least-norm solutions of consistent linear equations, Linear Algebra Appl. 43 (1982), 223–226, 10.1016/0024-3795(82)90255-5.Search in Google Scholar
[30] J. Ji, Explicit expressions of the generalized inverses and condensed Cramer rules, Linear Algebra Appl. 404 (2005), 183–192, 10.1016/j.laa.2005.02.025.Search in Google Scholar
[31] I. Kyrchei, Analogs of Cramer’s rule for the minimum norm least squares solutions of some matrix equations, Appl. Math. Comput. 218 (2012), no. 11, 6375–6384, 10.1016/j.amc.2011.12.004.Search in Google Scholar
[32] I. Kyrchei, Explicit formulas for determinantal representations of the Drazin inverse solutions of some matrix and differential matrix equations, Appl. Math. Comput. 219 (2013), no. 14, 7632–7644, 10.1016/j.amc.2013.01.050.Search in Google Scholar
[33] I. Kyrchei, Cramer’s rule for generalized inverse solutions, in: I. Kyrchei (Ed.), Advances in Linear Algebra Research, pp. 79–132, Nova Science Publishers, New York, 2015.Search in Google Scholar
[34] I. Kyrchei, Weighted singular value decomposition and determinantal representations of the quaternion weighted Moore-Penrose inverse, Appl. Math. Comput. 309 (2017), 1–16, 10.1016/j.amc.2017.03.048.Search in Google Scholar
[35] J. Ji, A condensed Cramer’s rule for the minimum-norm least-squares solution of linear equations, Linear Algebra Appl. 437 (2012), no. 9, 2173–2178, 10.1016/j.laa.2012.06.012.Search in Google Scholar
[36] G. Wang and Z. Xu, Solving a kind of restricted matrix equations and Cramer rule, Appl. Math. Comput. 162 (2005), no. 1, 329–338, 10.1016/j.amc.2003.12.118.Search in Google Scholar
© 2020 Hongxing Wang and Xiaoyan Zhang, published by De Gruyter
This work is licensed under the Creative Commons Attribution 4.0 International License.