LAPACK: TESTING/LIN/slatb5.f Source File

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00001       SUBROUTINE SLATB5( PATH, IMAT, N, TYPE, KL, KU, ANORM, MODE,
00002      $                   CNDNUM, DIST )
00003 *
00004 *  -- LAPACK test routine (version 3.1) --
00005 *     Craig Lucas, University of Manchester / NAG Ltd.
00006 *     October, 2008
00007 *
00008 *     .. Scalar Arguments ..
00009       REAL               ANORM, CNDNUM
00010       INTEGER            IMAT, KL, KU, MODE, N
00011       CHARACTER          DIST, TYPE
00012       CHARACTER*3        PATH
00013 *     ..
00014 *
00015 *  Purpose
00016 *  =======
00017 *
00018 *  SLATB5 sets parameters for the matrix generator based on the type
00019 *  of matrix to be generated.
00020 *
00021 *  Arguments
00022 *  =========
00023 *
00024 *  PATH    (input) CHARACTER*3
00025 *          The LAPACK path name.
00026 *
00027 *  IMAT    (input) INTEGER
00028 *          An integer key describing which matrix to generate for this
00029 *          path.
00030 *
00031 *  N       (input) INTEGER
00032 *          The number of rows and columns in the matrix to be generated.
00033 *
00034 *  TYPE    (output) CHARACTER*1
00035 *          The type of the matrix to be generated:
00036 *          = 'S':  symmetric matrix
00037 *          = 'P':  symmetric positive (semi)definite matrix
00038 *          = 'N':  nonsymmetric matrix
00039 *
00040 *  KL      (output) INTEGER
00041 *          The lower band width of the matrix to be generated.
00042 *
00043 *  KU      (output) INTEGER
00044 *          The upper band width of the matrix to be generated.
00045 *
00046 *  ANORM   (output) REAL
00047 *          The desired norm of the matrix to be generated.  The diagonal
00048 *          matrix of singular values or eigenvalues is scaled by this
00049 *          value.
00050 *
00051 *  MODE    (output) INTEGER
00052 *          A key indicating how to choose the vector of eigenvalues.
00053 *
00054 *  CNDNUM  (output) REAL
00055 *          The desired condition number.
00056 *
00057 *  DIST    (output) CHARACTER*1
00058 *          The type of distribution to be used by the random number
00059 *          generator.
00060 *
00061 *  =====================================================================
00062 *
00063 *     .. Parameters ..
00064       REAL               SHRINK, TENTH
00065       PARAMETER          ( SHRINK = 0.25E0, TENTH = 0.1E+0 )
00066       REAL               ONE
00067       PARAMETER          ( ONE = 1.0E+0 )
00068       REAL               TWO
00069       PARAMETER          ( TWO = 2.0E+0 )
00070 *     ..
00071 *     .. Local Scalars ..
00072       REAL               BADC1, BADC2, EPS, LARGE, SMALL
00073       LOGICAL            FIRST
00074       CHARACTER*2        C2
00075 *     ..
00076 *     .. External Functions ..
00077       REAL               SLAMCH
00078       EXTERNAL           SLAMCH
00079 *     ..
00080 *     .. Intrinsic Functions ..
00081       INTRINSIC          MAX, SQRT
00082 *     ..
00083 *     .. External Subroutines ..
00084       EXTERNAL           SLABAD
00085 *     ..
00086 *     .. Save statement ..
00087       SAVE               EPS, SMALL, LARGE, BADC1, BADC2, FIRST
00088 *     ..
00089 *     .. Data statements ..
00090       DATA               FIRST / .TRUE. /
00091 *     ..
00092 *     .. Executable Statements ..
00093 *
00094 *     Set some constants for use in the subroutine.
00095 *
00096       IF( FIRST ) THEN
00097          FIRST = .FALSE.
00098          EPS = SLAMCH( 'Precision' )
00099          BADC2 = TENTH / EPS
00100          BADC1 = SQRT( BADC2 )
00101          SMALL = SLAMCH( 'Safe minimum' )
00102          LARGE = ONE / SMALL
00103 *
00104 *        If it looks like we're on a Cray, take the square root of
00105 *        SMALL and LARGE to avoid overflow and underflow problems.
00106 *
00107          CALL SLABAD( SMALL, LARGE )
00108          SMALL = SHRINK*( SMALL / EPS )
00109          LARGE = ONE / SMALL
00110       END IF
00111 *
00112       C2 = PATH( 2: 3 )
00113 *
00114 *     Set some parameters
00115 *
00116       DIST = 'S'
00117       MODE = 3
00118 *
00119 *     Set TYPE, the type of matrix to be generated.
00120 *
00121       TYPE = C2( 1: 1 )
00122 *
00123 *     Set the lower and upper bandwidths.
00124 *
00125       IF( IMAT.EQ.1 ) THEN
00126          KL = 0
00127       ELSE
00128          KL = MAX( N-1, 0 )
00129       END IF
00130       KU = KL
00131 *
00132 *     Set the condition number and norm.etc
00133 *
00134       IF( IMAT.EQ.3 ) THEN
00135          CNDNUM = 1.0E4
00136          MODE = 2
00137       ELSE IF( IMAT.EQ.4 ) THEN
00138          CNDNUM = 1.0E4
00139          MODE = 1
00140       ELSE IF( IMAT.EQ.5 ) THEN
00141          CNDNUM = 1.0E4
00142          MODE = 3
00143       ELSE IF( IMAT.EQ.6 ) THEN
00144          CNDNUM = BADC1
00145       ELSE IF( IMAT.EQ.7 ) THEN
00146          CNDNUM = BADC2
00147       ELSE
00148          CNDNUM = TWO
00149       END IF
00150 *
00151       IF( IMAT.EQ.8 ) THEN
00152          ANORM = SMALL
00153       ELSE IF( IMAT.EQ.9 ) THEN
00154          ANORM = LARGE
00155       ELSE
00156          ANORM = ONE
00157       END IF
00158 *
00159       IF( N.LE.1 )
00160      $   CNDNUM = ONE
00161 *
00162       RETURN
00163 *
00164 *     End of SLATB5
00165 *
00166       END