FLASH_Apply_Q_UT_create_workspace.c File Reference

(r)

Functions
FLA_Error	FLASH_Apply_Q_UT_create_workspace (FLA_Obj TW, FLA_Obj B, FLA_Obj *W)

---

Function Documentation

FLA_Error FLASH_Apply_Q_UT_create_workspace	(	FLA_Obj	TW,
		FLA_Obj	B,
		FLA_Obj *	W
	)

References FLA_Abort(), FLA_Obj_datatype(), FLA_Print_message(), FLASH_Obj_create_ext(), FLASH_Obj_depth(), FLASH_Obj_scalar_length_tl(), FLASH_Obj_scalar_width(), and FLASH_Obj_scalar_width_tl().

Referenced by FLASH_LQ_UT_solve(), and FLASH_QR_UT_solve().

{
    FLA_Datatype datatype;
    dim_t        depth;
    dim_t        b_alg;
    dim_t        b_flash;
    dim_t        m, n;

    // Query the depth.
    depth = FLASH_Obj_depth( TW );

    // *** The current Apply_Q_UT algorithm implemented assumes that
    // the matrix has a hierarchical depth of 1. We check for that here
    // because we anticipate that we'll use a more general algorithm in the
    // future, and we don't want to forget to remove the constraint. ***
    if ( depth != 1 )
    {
       FLA_Print_message( "FLASH_Apply_Q_UT() currently only supports matrices of depth 1",
                          __FILE__, __LINE__ );
       FLA_Abort();
    }

    // Query the datatype of matrix TW.
    datatype = FLA_Obj_datatype( TW );

    // Inspect the dimensions of a the top-left element of TW to get the
    // algorithmic/storage blocksize we'll use throughout the Apply_Q_UT
    // algorithm.
    b_alg   = FLASH_Obj_scalar_length_tl( TW );
    b_flash = FLASH_Obj_scalar_width_tl( TW );

    // The traditional (non-incremental) Apply_Q_UT algorithm-by-blocks
    // requires that the algorithmic blocksize be equal to the storage
    // blocksize.
    if ( b_alg != b_flash )
    {
        FLA_Print_message( "FLASH_Apply_Q_UT() requires that b_alg == b_store",
                           __FILE__, __LINE__ );
        FLA_Abort();
    }

    // The scalar length of W should be the algorithmc/storage blocksize
    // encoded in TW.
    m = b_alg;

    // Query the scalar (not element) width of the right-hand side
    // matrix B.
    n = FLASH_Obj_scalar_width( B );

    // Create hierarchical matrix W.
    FLASH_Obj_create_ext( datatype, m, n, 
                          depth, &b_alg, &b_flash, 
                          W );
   
    return FLA_SUCCESS;
}