1 /*
2
3 Copyright (C) 2014, The University of Texas at Austin
4
5 This file is part of libflame and is available under the 3-Clause
6 BSD license, which can be found in the LICENSE file at the top-level
7 directory, or at http://opensource.org/licenses/BSD-3-Clause
8
9 */
10
11 #include "FLAME.h"
12
13 #ifdef FLA_ENABLE_NON_CRITICAL_CODE
14
FLA_Chol_l_unb_var1(FLA_Obj A)15 FLA_Error FLA_Chol_l_unb_var1( FLA_Obj A )
16 {
17 FLA_Obj ATL, ATR, A00, a01, A02,
18 ABL, ABR, a10t, alpha11, a12t,
19 A20, a21, A22;
20
21 int r_val = FLA_SUCCESS;
22
23 FLA_Part_2x2( A, &ATL, &ATR,
24 &ABL, &ABR, 0, 0, FLA_TL );
25
26 while ( FLA_Obj_length( ATL ) < FLA_Obj_length( A ) ){
27
28 FLA_Repart_2x2_to_3x3( ATL, /**/ ATR, &A00, /**/ &a01, &A02,
29 /* ************* */ /* ************************** */
30 &a10t, /**/ &alpha11, &a12t,
31 ABL, /**/ ABR, &A20, /**/ &a21, &A22,
32 1, 1, FLA_BR );
33
34 /*------------------------------------------------------------*/
35
36 // a10t = a10t * inv( tril( A00 )' )
37 // a10t' = inv( conj( tril( A00 ) ) ) * a10t'
38 FLA_Trsv_external( FLA_LOWER_TRIANGULAR, FLA_CONJ_NO_TRANSPOSE, FLA_NONUNIT_DIAG, A00, a10t );
39
40 // alpha11 = alpha11 - a10t * a10t'
41 FLA_Dotcs_external( FLA_CONJUGATE, FLA_MINUS_ONE, a10t, a10t, FLA_ONE, alpha11 );
42
43 // alpha11 = sqrt( alpha11 )
44 r_val = FLA_Sqrt( alpha11 );
45
46 if ( r_val != FLA_SUCCESS )
47 return ( FLA_Obj_length( A00 ) );
48
49 /*------------------------------------------------------------*/
50
51 FLA_Cont_with_3x3_to_2x2( &ATL, /**/ &ATR, A00, a01, /**/ A02,
52 a10t, alpha11, /**/ a12t,
53 /* ************** */ /* ************************ */
54 &ABL, /**/ &ABR, A20, a21, /**/ A22,
55 FLA_TL );
56 }
57
58 return r_val;
59 }
60
61 #endif
62