pb_lmul()

subroutine pb_lmul	(	integer, dimension( 2 )	k,
		integer, dimension( 2 )	j,
		integer, dimension( 2 )	i
	)

Definition at line 4558 of file pblastst.f.

*
*  -- PBLAS test routine (version 2.0) --
*     University of Tennessee, Knoxville, Oak Ridge National Laboratory,
*     and University of California, Berkeley.
*     April 1, 1998
*
*     .. Array Arguments ..
      INTEGER            I( 2 ), J( 2 ), K( 2 )
*     ..
*
*  Purpose
*  =======
*
*  PB_LMUL  multiplies  without carry two long positive integers K and J
*  and put the result into I.  The long integers  I, J, K are encoded on
*  31 bits using an array of 2 integers. The 16-lower bits are stored in
*  the first entry of each array, the 15-higher bits in the second entry
*  of each array. For efficiency purposes, the  intrisic modulo function
*  is inlined.
*
*  Arguments
*  =========
*
*  K       (local input) INTEGER array
*          On entry, K is an array of dimension 2 containing the encoded
*          long integer K.
*
*  J       (local input) INTEGER array
*          On entry, J is an array of dimension 2 containing the encoded
*          long integer J.
*
*  I       (local output) INTEGER array
*          On entry, I is an array of dimension 2. On exit,  this  array
*          contains the encoded long integer I.
*
*  Further Details
*  ===============
*
*            K( 2 )   K( 1 )
*          0XXXXXXX XXXXXXXX  K   I( 1 ) = MOD( K( 1 ) + J( 1 ), 2**16 )
*        *                        carry  = ( K( 1 ) + J( 1 ) ) / 2**16
*            J( 2 )   J( 1 )
*          0XXXXXXX XXXXXXXX  J   I( 2 ) = K( 2 ) + J( 2 ) + carry
*        ----------------------   I( 2 ) = MOD( I( 2 ), 2**15 )
*            I( 2 )   I( 1 )
*          0XXXXXXX XXXXXXXX  I
*
*  -- Written on April 1, 1998 by
*     Antoine Petitet, University  of  Tennessee, Knoxville 37996, USA.
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            IPOW15, IPOW16, IPOW30
      parameter( ipow15 = 2**15, ipow16 = 2**16,
     $                   ipow30 = 2**30 )
*     ..
*     .. Local Scalars ..
      INTEGER            ITMP1, ITMP2
*     ..
*     .. Executable Statements ..
*
      itmp1 = k( 1 ) * j( 1 )
      IF( itmp1.LT.0 )
     $   itmp1 = ( itmp1 + ipow30 ) + ipow30
*
*     I( 1 ) = MOD( ITMP1, IPOW16 )
*
      itmp2 = itmp1 / ipow16
      i( 1 ) = itmp1 - itmp2 * ipow16
*
      itmp1 = k( 1 ) * j( 2 ) + k( 2 ) * j( 1 )
      IF( itmp1.LT.0 )
     $   itmp1 = ( itmp1 + ipow30 ) + ipow30
*
      itmp1 = itmp2 + itmp1
      IF( itmp1.LT.0 )
     $   itmp1 = ( itmp1 + ipow30 ) + ipow30
*
*     I( 2 ) = MOD( ITMP1, IPOW15 )
*
      i( 2 ) = itmp1 - ( itmp1 / ipow15 ) * ipow15
*
      RETURN
*
*     End of PB_LMUL
*

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