219 SUBROUTINE sspt21( ITYPE, UPLO, N, KBAND, AP, D, E, U, LDU, VP,
220 $ tau, work, result )
229 INTEGER itype, kband, ldu, n
232 REAL ap( * ), d( * ), e( * ), result( 2 ), tau( * ),
233 $ u( ldu, * ), vp( * ), work( * )
240 parameter( zero = 0.0e0, one = 1.0e0, ten = 10.0e0 )
242 parameter( half = 1.0e+0 / 2.0e+0 )
247 INTEGER iinfo,
j, jp, jp1, jr, lap
248 REAL anorm, temp, ulp, unfl, vsave, wnorm
260 INTRINSIC max, min, real
272 lap = ( n*( n+1 ) ) / 2
274 IF(
lsame( uplo,
'U' ) )
THEN
282 unfl =
slamch(
'Safe minimum' )
287 IF( itype.LT.1 .OR. itype.GT.3 )
THEN
288 result( 1 ) = ten / ulp
296 IF( itype.EQ.3 )
THEN
299 anorm = max(
slansp(
'1', cuplo, n, ap, work ), unfl )
304 IF( itype.EQ.1 )
THEN
308 CALL
slaset(
'Full', n, n, zero, zero, work, n )
309 CALL
scopy( lap, ap, 1, work, 1 )
312 CALL
sspr( cuplo, n, -d(
j ), u( 1,
j ), 1, work )
315 IF( n.GT.1 .AND. kband.EQ.1 )
THEN
317 CALL
sspr2( cuplo, n, -e(
j ), u( 1,
j ), 1, u( 1,
j+1 ),
321 wnorm =
slansp(
'1', cuplo, n, work, work( n**2+1 ) )
323 ELSE IF( itype.EQ.2 )
THEN
327 CALL
slaset(
'Full', n, n, zero, zero, work, n )
331 DO 40
j = n - 1, 1, -1
332 jp = ( ( 2*n-
j )*(
j-1 ) ) / 2
334 IF( kband.EQ.1 )
THEN
335 work( jp+
j+1 ) = ( one-tau(
j ) )*e(
j )
337 work( jp+jr ) = -tau(
j )*e(
j )*vp( jp+jr )
341 IF( tau(
j ).NE.zero )
THEN
344 CALL
sspmv(
'L', n-
j, one, work( jp1+
j+1 ),
345 $ vp( jp+
j+1 ), 1, zero, work( lap+1 ), 1 )
346 temp = -half*tau(
j )*
sdot( n-
j, work( lap+1 ), 1,
348 CALL
saxpy( n-
j, temp, vp( jp+
j+1 ), 1, work( lap+1 ),
350 CALL
sspr2(
'L', n-
j, -tau(
j ), vp( jp+
j+1 ), 1,
351 $ work( lap+1 ), 1, work( jp1+
j+1 ) )
354 work( jp+
j ) = d(
j )
359 jp = (
j*(
j-1 ) ) / 2
361 IF( kband.EQ.1 )
THEN
362 work( jp1+
j ) = ( one-tau(
j ) )*e(
j )
364 work( jp1+jr ) = -tau(
j )*e(
j )*vp( jp1+jr )
368 IF( tau(
j ).NE.zero )
THEN
371 CALL
sspmv(
'U',
j, one, work, vp( jp1+1 ), 1, zero,
373 temp = -half*tau(
j )*
sdot(
j, work( lap+1 ), 1,
375 CALL
saxpy(
j, temp, vp( jp1+1 ), 1, work( lap+1 ),
377 CALL
sspr2(
'U',
j, -tau(
j ), vp( jp1+1 ), 1,
378 $ work( lap+1 ), 1, work )
381 work( jp1+
j+1 ) = d(
j+1 )
386 work(
j ) = work(
j ) - ap(
j )
388 wnorm =
slansp(
'1', cuplo, n, work, work( lap+1 ) )
390 ELSE IF( itype.EQ.3 )
THEN
396 CALL
slacpy(
' ', n, n, u, ldu, work, n )
397 CALL
sopmtr(
'R', cuplo,
'T', n, n, vp, tau, work, n,
398 $ work( n**2+1 ), iinfo )
399 IF( iinfo.NE.0 )
THEN
400 result( 1 ) = ten / ulp
405 work( ( n+1 )*(
j-1 )+1 ) = work( ( n+1 )*(
j-1 )+1 ) - one
408 wnorm =
slange(
'1', n, n, work, n, work( n**2+1 ) )
411 IF( anorm.GT.wnorm )
THEN
412 result( 1 ) = ( wnorm / anorm ) / ( n*ulp )
414 IF( anorm.LT.one )
THEN
415 result( 1 ) = ( min( wnorm, n*anorm ) / anorm ) / ( n*ulp )
417 result( 1 ) = min( wnorm / anorm,
REAL( N ) ) / ( n*ulp )
425 IF( itype.EQ.1 )
THEN
426 CALL
sgemm(
'N',
'C', n, n, n, one, u, ldu, u, ldu, zero, work,
430 work( ( n+1 )*(
j-1 )+1 ) = work( ( n+1 )*(
j-1 )+1 ) - one
433 result( 2 ) = min(
slange(
'1', n, n, work, n,
434 $ work( n**2+1 ) ),
REAL( N ) ) / ( n*ulp )