LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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◆ zqrt13()

subroutine zqrt13 ( integer  SCALE,
integer  M,
integer  N,
complex*16, dimension( lda, * )  A,
integer  LDA,
double precision  NORMA,
integer, dimension( 4 )  ISEED 
)

ZQRT13

Purpose:
 ZQRT13 generates a full-rank matrix that may be scaled to have large
 or small norm.
Parameters
[in]SCALE
          SCALE is INTEGER
          SCALE = 1: normally scaled matrix
          SCALE = 2: matrix scaled up
          SCALE = 3: matrix scaled down
[in]M
          M is INTEGER
          The number of rows of the matrix A.
[in]N
          N is INTEGER
          The number of columns of A.
[out]A
          A is COMPLEX*16 array, dimension (LDA,N)
          The M-by-N matrix A.
[in]LDA
          LDA is INTEGER
          The leading dimension of the array A.
[out]NORMA
          NORMA is DOUBLE PRECISION
          The one-norm of A.
[in,out]ISEED
          ISEED is integer array, dimension (4)
          Seed for random number generator
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.

Definition at line 90 of file zqrt13.f.

91*
92* -- LAPACK test routine --
93* -- LAPACK is a software package provided by Univ. of Tennessee, --
94* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
95*
96* .. Scalar Arguments ..
97 INTEGER LDA, M, N, SCALE
98 DOUBLE PRECISION NORMA
99* ..
100* .. Array Arguments ..
101 INTEGER ISEED( 4 )
102 COMPLEX*16 A( LDA, * )
103* ..
104*
105* =====================================================================
106*
107* .. Parameters ..
108 DOUBLE PRECISION ONE
109 parameter( one = 1.0d0 )
110* ..
111* .. Local Scalars ..
112 INTEGER INFO, J
113 DOUBLE PRECISION BIGNUM, SMLNUM
114* ..
115* .. External Functions ..
116 DOUBLE PRECISION DLAMCH, DZASUM, ZLANGE
117 EXTERNAL dlamch, dzasum, zlange
118* ..
119* .. External Subroutines ..
120 EXTERNAL dlabad, zlarnv, zlascl
121* ..
122* .. Intrinsic Functions ..
123 INTRINSIC dble, dcmplx, sign
124* ..
125* .. Local Arrays ..
126 DOUBLE PRECISION DUMMY( 1 )
127* ..
128* .. Executable Statements ..
129*
130 IF( m.LE.0 .OR. n.LE.0 )
131 $ RETURN
132*
133* benign matrix
134*
135 DO 10 j = 1, n
136 CALL zlarnv( 2, iseed, m, a( 1, j ) )
137 IF( j.LE.m ) THEN
138 a( j, j ) = a( j, j ) + dcmplx( sign( dzasum( m, a( 1, j ),
139 $ 1 ), dble( a( j, j ) ) ) )
140 END IF
141 10 CONTINUE
142*
143* scaled versions
144*
145 IF( scale.NE.1 ) THEN
146 norma = zlange( 'Max', m, n, a, lda, dummy )
147 smlnum = dlamch( 'Safe minimum' )
148 bignum = one / smlnum
149 CALL dlabad( smlnum, bignum )
150 smlnum = smlnum / dlamch( 'Epsilon' )
151 bignum = one / smlnum
152*
153 IF( scale.EQ.2 ) THEN
154*
155* matrix scaled up
156*
157 CALL zlascl( 'General', 0, 0, norma, bignum, m, n, a, lda,
158 $ info )
159 ELSE IF( scale.EQ.3 ) THEN
160*
161* matrix scaled down
162*
163 CALL zlascl( 'General', 0, 0, norma, smlnum, m, n, a, lda,
164 $ info )
165 END IF
166 END IF
167*
168 norma = zlange( 'One-norm', m, n, a, lda, dummy )
169 RETURN
170*
171* End of ZQRT13
172*
dlamch
double precision function dlamch(CMACH)
DLAMCH
Definition: dlamch.f:69
dlabad
subroutine dlabad(SMALL, LARGE)
DLABAD
Definition: dlabad.f:74
zlange
double precision function zlange(NORM, M, N, A, LDA, WORK)
ZLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value ...
Definition: zlange.f:115
zlascl
subroutine zlascl(TYPE, KL, KU, CFROM, CTO, M, N, A, LDA, INFO)
ZLASCL multiplies a general rectangular matrix by a real scalar defined as cto/cfrom.
Definition: zlascl.f:143
zlarnv
subroutine zlarnv(IDIST, ISEED, N, X)
ZLARNV returns a vector of random numbers from a uniform or normal distribution.
Definition: zlarnv.f:99
dzasum
double precision function dzasum(N, ZX, INCX)
DZASUM
Definition: dzasum.f:72
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