libflame
revision_anchor
|
Functions | |
FLA_Error | FLA_Svd_compute_scaling (FLA_Obj A, FLA_Obj sigma) |
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().
{ FLA_Datatype dt_real; FLA_Obj norm; FLA_Obj safmin; FLA_Obj prec; FLA_Obj rmin; FLA_Obj rmax; if ( FLA_Check_error_level() >= FLA_MIN_ERROR_CHECKING ) FLA_Svd_compute_scaling_check( A, sigma ); dt_real = FLA_Obj_datatype_proj_to_real( A ); FLA_Obj_create( dt_real, 1, 1, 0, 0, &norm ); FLA_Obj_create( dt_real, 1, 1, 0, 0, &prec ); FLA_Obj_create( dt_real, 1, 1, 0, 0, &safmin ); FLA_Obj_create( dt_real, 1, 1, 0, 0, &rmin ); FLA_Obj_create( dt_real, 1, 1, 0, 0, &rmax ); // Query safmin, precision. FLA_Mach_params( FLA_MACH_PREC, prec ); FLA_Mach_params( FLA_MACH_SFMIN, safmin ); //FLA_Obj_show( "safmin", safmin, "%20.12e", "" ); //FLA_Obj_show( "prec", prec, "%20.12e", "" ); // rmin = sqrt( safmin ) / prec; FLA_Copy( safmin, rmin ); FLA_Sqrt( rmin ); FLA_Inv_scal( prec, rmin ); // rmax = 1 / rmin; FLA_Copy( rmin, rmax ); FLA_Invert( FLA_NO_CONJUGATE, rmax ); //FLA_Obj_show( "rmin", rmin, "%20.12e", "" ); //FLA_Obj_show( "rmax", rmax, "%20.12e", "" ); // Find the maximum absolute value of A. FLA_Max_abs_value( A, norm ); if ( FLA_Obj_gt( norm, FLA_ZERO ) && FLA_Obj_lt( norm, rmin ) ) { // sigma = rmin / norm; FLA_Copy( rmin, sigma ); FLA_Inv_scal( norm, sigma ); } else if ( FLA_Obj_gt( norm, rmax ) ) { // sigma = rmax / norm; FLA_Copy( rmax, sigma ); FLA_Inv_scal( norm, sigma ); } else { // sigma = 1.0; FLA_Copy( FLA_ONE, sigma ); } FLA_Obj_free( &norm ); FLA_Obj_free( &prec ); FLA_Obj_free( &safmin ); FLA_Obj_free( &rmin ); FLA_Obj_free( &rmax ); return FLA_SUCCESS; }