FLASH_QR_UT_inc_solve.c File Reference

(r)

Functions
FLA_Error	FLASH_QR_UT_inc_solve (FLA_Obj A, FLA_Obj TW, FLA_Obj B, FLA_Obj X)

---

Function Documentation

FLA_Error FLASH_QR_UT_inc_solve	(	FLA_Obj	A,
		FLA_Obj	TW,
		FLA_Obj	B,
		FLA_Obj	X
	)

References FLA_Check_error_level(), FLA_ONE, FLA_QR_UT_inc_solve_check(), FLASH_Apply_Q_UT_inc(), FLASH_Apply_Q_UT_inc_create_workspace(), FLASH_Copy(), FLASH_Obj_create_copy_of(), FLASH_Obj_free(), FLASH_Obj_scalar_width(), FLASH_Part_create_2x1(), FLASH_Part_free_2x1(), and FLASH_Trsm().

{
  FLA_Obj W, Y;
  FLA_Obj AT, AB;
  FLA_Obj YT, YB;

  // Check parameters.
  if ( FLA_Check_error_level() >= FLA_MIN_ERROR_CHECKING )
    FLA_QR_UT_inc_solve_check( A, TW, B, X );

  FLASH_Apply_Q_UT_inc_create_workspace( TW, B, &W );

  FLASH_Obj_create_copy_of( FLA_NO_TRANSPOSE, B, &Y );

  FLASH_Apply_Q_UT_inc( FLA_LEFT, FLA_CONJ_TRANSPOSE, FLA_FORWARD, FLA_COLUMNWISE,
                        A, TW, W, Y );

  // Create a temporary hierarchical view of only the top n-by-n part of A in
  // case m > n so that AT captures the upper triangular factor R. We do the
  // same for Y to ensure conformality.
  FLASH_Part_create_2x1( A,   &AT,    
                              &AB,    FLASH_Obj_scalar_width( A ), FLA_TOP );
  FLASH_Part_create_2x1( Y,   &YT,    
                              &YB,    FLASH_Obj_scalar_width( A ), FLA_TOP );

  FLASH_Trsm( FLA_LEFT, FLA_UPPER_TRIANGULAR, FLA_NO_TRANSPOSE, FLA_NONUNIT_DIAG,
              FLA_ONE, AT, YT );

  FLASH_Copy( YT, X );

  // Free the temporary hierarchical views.
  FLASH_Part_free_2x1( &AT,
                       &AB );
  FLASH_Part_free_2x1( &YT,
                       &YB );

  FLASH_Obj_free( &Y );
  FLASH_Obj_free( &W );

  return FLA_SUCCESS;
}