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SUBROUTINE CLATB5( PATH, IMAT, N, TYPE, KL, KU, ANORM, MODE,
$ CNDNUM, DIST )
*
* -- LAPACK test routine (version 3.1) --
* Craig Lucas, University of Manchester / NAG Ltd.
* October, 2008
*
* .. Scalar Arguments ..
REAL ANORM, CNDNUM
INTEGER IMAT, KL, KU, MODE, N
CHARACTER DIST, TYPE
CHARACTER*3 PATH
* ..
*
* Purpose
* =======
*
* CLATB5 sets parameters for the matrix generator based on the type
* of matrix to be generated.
*
* Arguments
* =========
*
* PATH (input) CHARACTER*3
* The LAPACK path name.
*
* IMAT (input) INTEGER
* An integer key describing which matrix to generate for this
* path.
*
* N (input) INTEGER
* The number of rows and columns in the matrix to be generated.
*
* TYPE (output) CHARACTER*1
* The type of the matrix to be generated:
* = 'S': symmetric matrix
* = 'P': symmetric positive (semi)definite matrix
* = 'N': nonsymmetric matrix
*
* KL (output) INTEGER
* The lower band width of the matrix to be generated.
*
* KU (output) INTEGER
* The upper band width of the matrix to be generated.
*
* ANORM (output) REAL
* The desired norm of the matrix to be generated. The diagonal
* matrix of singular values or eigenvalues is scaled by this
* value.
*
* MODE (output) INTEGER
* A key indicating how to choose the vector of eigenvalues.
*
* CNDNUM (output) REAL
* The desired condition number.
*
* DIST (output) CHARACTER*1
* The type of distribution to be used by the random number
* generator.
*
* =====================================================================
*
* .. Parameters ..
REAL SHRINK, TENTH
PARAMETER ( SHRINK = 0.25E0, TENTH = 0.1E+0 )
REAL ONE
PARAMETER ( ONE = 1.0E+0 )
REAL TWO
PARAMETER ( TWO = 2.0E+0 )
* ..
* .. Local Scalars ..
REAL BADC1, BADC2, EPS, LARGE, SMALL
LOGICAL FIRST
CHARACTER*2 C2
* ..
* .. External Functions ..
REAL SLAMCH
EXTERNAL SLAMCH
* ..
* .. Intrinsic Functions ..
INTRINSIC MAX, SQRT
* ..
* .. External Subroutines ..
EXTERNAL SLABAD
* ..
* .. Save statement ..
SAVE EPS, SMALL, LARGE, BADC1, BADC2, FIRST
* ..
* .. Data statements ..
DATA FIRST / .TRUE. /
* ..
* .. Executable Statements ..
*
* Set some constants for use in the subroutine.
*
IF( FIRST ) THEN
FIRST = .FALSE.
EPS = SLAMCH( 'Precision' )
BADC2 = TENTH / EPS
BADC1 = SQRT( BADC2 )
SMALL = SLAMCH( 'Safe minimum' )
LARGE = ONE / SMALL
*
* If it looks like we're on a Cray, take the square root of
* SMALL and LARGE to avoid overflow and underflow problems.
*
CALL SLABAD( SMALL, LARGE )
SMALL = SHRINK*( SMALL / EPS )
LARGE = ONE / SMALL
END IF
*
C2 = PATH( 2: 3 )
*
* Set some parameters
*
DIST = 'S'
MODE = 3
*
* Set TYPE, the type of matrix to be generated.
*
TYPE = C2( 1: 1 )
*
* Set the lower and upper bandwidths.
*
IF( IMAT.EQ.1 ) THEN
KL = 0
ELSE
KL = MAX( N-1, 0 )
END IF
KU = KL
*
* Set the condition number and norm.etc
*
IF( IMAT.EQ.3 ) THEN
CNDNUM = 1.0E4
MODE = 2
ELSE IF( IMAT.EQ.4 ) THEN
CNDNUM = 1.0E4
MODE = 1
ELSE IF( IMAT.EQ.5 ) THEN
CNDNUM = 1.0E4
MODE = 3
ELSE IF( IMAT.EQ.6 ) THEN
CNDNUM = BADC1
ELSE IF( IMAT.EQ.7 ) THEN
CNDNUM = BADC2
ELSE
CNDNUM = TWO
END IF
*
IF( IMAT.EQ.8 ) THEN
ANORM = SMALL
ELSE IF( IMAT.EQ.9 ) THEN
ANORM = LARGE
ELSE
ANORM = ONE
END IF
*
IF( N.LE.1 )
$ CNDNUM = ONE
*
RETURN
*
* End of SLATB5
*
END
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