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Functions
FLA_Svd_compute_scaling.c File Reference

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Functions

FLA_Error FLA_Svd_compute_scaling (FLA_Obj A, FLA_Obj sigma)
 

Function Documentation

◆ FLA_Svd_compute_scaling()

FLA_Error FLA_Svd_compute_scaling ( FLA_Obj  A,
FLA_Obj  sigma 
)

References FLA_Check_error_level(), FLA_Copy(), FLA_Inv_scal(), FLA_Invert(), FLA_Mach_params(), FLA_Max_abs_value(), FLA_Obj_create(), FLA_Obj_datatype_proj_to_real(), FLA_Obj_free(), FLA_Obj_gt(), FLA_Obj_lt(), FLA_ONE, FLA_Sqrt(), FLA_Svd_compute_scaling_check(), and FLA_ZERO.

Referenced by FLA_Svd_uv_unb_var1(), and FLA_Svd_uv_unb_var2().

14 {
15  FLA_Datatype dt_real;
16  FLA_Obj norm;
17  FLA_Obj safmin;
18  FLA_Obj prec;
19  FLA_Obj rmin;
20  FLA_Obj rmax;
21 
22  if ( FLA_Check_error_level() >= FLA_MIN_ERROR_CHECKING )
24 
25  dt_real = FLA_Obj_datatype_proj_to_real( A );
26 
27  FLA_Obj_create( dt_real, 1, 1, 0, 0, &norm );
28  FLA_Obj_create( dt_real, 1, 1, 0, 0, &prec );
29  FLA_Obj_create( dt_real, 1, 1, 0, 0, &safmin );
30  FLA_Obj_create( dt_real, 1, 1, 0, 0, &rmin );
31  FLA_Obj_create( dt_real, 1, 1, 0, 0, &rmax );
32 
33  // Query safmin, precision.
34  FLA_Mach_params( FLA_MACH_PREC, prec );
35  FLA_Mach_params( FLA_MACH_SFMIN, safmin );
36 
37 //FLA_Obj_show( "safmin", safmin, "%20.12e", "" );
38 //FLA_Obj_show( "prec", prec, "%20.12e", "" );
39 
40  // rmin = sqrt( safmin ) / prec;
41  FLA_Copy( safmin, rmin );
42  FLA_Sqrt( rmin );
43  FLA_Inv_scal( prec, rmin );
44 
45  // rmax = 1 / rmin;
46  FLA_Copy( rmin, rmax );
47  FLA_Invert( FLA_NO_CONJUGATE, rmax );
48 
49 //FLA_Obj_show( "rmin", rmin, "%20.12e", "" );
50 //FLA_Obj_show( "rmax", rmax, "%20.12e", "" );
51 
52  // Find the maximum absolute value of A.
53  FLA_Max_abs_value( A, norm );
54 
55  if ( FLA_Obj_gt( norm, FLA_ZERO ) && FLA_Obj_lt( norm, rmin ) )
56  {
57  // sigma = rmin / norm;
58  FLA_Copy( rmin, sigma );
59  FLA_Inv_scal( norm, sigma );
60  }
61  else if ( FLA_Obj_gt( norm, rmax ) )
62  {
63  // sigma = rmax / norm;
64  FLA_Copy( rmax, sigma );
65  FLA_Inv_scal( norm, sigma );
66  }
67  else
68  {
69  // sigma = 1.0;
70  FLA_Copy( FLA_ONE, sigma );
71  }
72 
73  FLA_Obj_free( &norm );
74  FLA_Obj_free( &prec );
75  FLA_Obj_free( &safmin );
76  FLA_Obj_free( &rmin );
77  FLA_Obj_free( &rmax );
78 
79  return FLA_SUCCESS;
80 }
FLA_Error FLA_Obj_create(FLA_Datatype datatype, dim_t m, dim_t n, dim_t rs, dim_t cs, FLA_Obj *obj)
Definition: FLA_Obj.c:55
FLA_Error FLA_Obj_free(FLA_Obj *obj)
Definition: FLA_Obj.c:588
FLA_Error FLA_Copy(FLA_Obj A, FLA_Obj B)
Definition: FLA_Copy.c:15
FLA_Bool FLA_Obj_gt(FLA_Obj A, FLA_Obj B)
Definition: FLA_Query.c:658
FLA_Error FLA_Max_abs_value(FLA_Obj A, FLA_Obj amax)
Definition: FLA_Max_abs_value.c:13
FLA_Obj FLA_ONE
Definition: FLA_Init.c:18
FLA_Bool FLA_Obj_lt(FLA_Obj A, FLA_Obj B)
Definition: FLA_Query.c:813
FLA_Error FLA_Mach_params(FLA_Machval machval, FLA_Obj val)
Definition: FLA_Mach_params.c:13
Definition: FLA_type_defs.h:158
FLA_Error FLA_Svd_compute_scaling_check(FLA_Obj A, FLA_Obj sigma)
Definition: FLA_Svd_compute_scaling_check.c:13
FLA_Error FLA_Invert(FLA_Conj conj, FLA_Obj x)
Definition: FLA_Invert.c:13
FLA_Datatype FLA_Obj_datatype_proj_to_real(FLA_Obj A)
Definition: FLA_Query.c:23
FLA_Error FLA_Inv_scal(FLA_Obj alpha, FLA_Obj A)
Definition: FLA_Inv_scal.c:13
unsigned int FLA_Check_error_level(void)
Definition: FLA_Check.c:18
int FLA_Datatype
Definition: FLA_type_defs.h:49
FLA_Error FLA_Sqrt(FLA_Obj alpha)
Definition: FLA_Sqrt.c:13
FLA_Obj FLA_ZERO
Definition: FLA_Init.c:20