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LAPACK 3.3.0
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LAPACK 3.3.0
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00001 SUBROUTINE CLATSY( UPLO, N, X, LDX, ISEED ) 00002 * 00003 * -- LAPACK auxiliary test routine (version 3.1) -- 00004 * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. 00005 * November 2006 00006 * 00007 * .. Scalar Arguments .. 00008 CHARACTER UPLO 00009 INTEGER LDX, N 00010 * .. 00011 * .. Array Arguments .. 00012 INTEGER ISEED( * ) 00013 COMPLEX X( LDX, * ) 00014 * .. 00015 * 00016 * Purpose 00017 * ======= 00018 * 00019 * CLATSY generates a special test matrix for the complex symmetric 00020 * (indefinite) factorization. The pivot blocks of the generated matrix 00021 * will be in the following order: 00022 * 2x2 pivot block, non diagonalizable 00023 * 1x1 pivot block 00024 * 2x2 pivot block, diagonalizable 00025 * (cycle repeats) 00026 * A row interchange is required for each non-diagonalizable 2x2 block. 00027 * 00028 * Arguments 00029 * ========= 00030 * 00031 * UPLO (input) CHARACTER 00032 * Specifies whether the generated matrix is to be upper or 00033 * lower triangular. 00034 * = 'U': Upper triangular 00035 * = 'L': Lower triangular 00036 * 00037 * N (input) INTEGER 00038 * The dimension of the matrix to be generated. 00039 * 00040 * X (output) COMPLEX array, dimension (LDX,N) 00041 * The generated matrix, consisting of 3x3 and 2x2 diagonal 00042 * blocks which result in the pivot sequence given above. 00043 * The matrix outside of these diagonal blocks is zero. 00044 * 00045 * LDX (input) INTEGER 00046 * The leading dimension of the array X. 00047 * 00048 * ISEED (input/output) INTEGER array, dimension (4) 00049 * On entry, the seed for the random number generator. The last 00050 * of the four integers must be odd. (modified on exit) 00051 * 00052 * ===================================================================== 00053 * 00054 * .. Parameters .. 00055 COMPLEX EYE 00056 PARAMETER ( EYE = ( 0.0, 1.0 ) ) 00057 * .. 00058 * .. Local Scalars .. 00059 INTEGER I, J, N5 00060 REAL ALPHA, ALPHA3, BETA 00061 COMPLEX A, B, C, R 00062 * .. 00063 * .. External Functions .. 00064 COMPLEX CLARND 00065 EXTERNAL CLARND 00066 * .. 00067 * .. Intrinsic Functions .. 00068 INTRINSIC ABS, SQRT 00069 * .. 00070 * .. Executable Statements .. 00071 * 00072 * Initialize constants 00073 * 00074 ALPHA = ( 1.+SQRT( 17. ) ) / 8. 00075 BETA = ALPHA - 1. / 1000. 00076 ALPHA3 = ALPHA*ALPHA*ALPHA 00077 * 00078 * UPLO = 'U': Upper triangular storage 00079 * 00080 IF( UPLO.EQ.'U' ) THEN 00081 * 00082 * Fill the upper triangle of the matrix with zeros. 00083 * 00084 DO 20 J = 1, N 00085 DO 10 I = 1, J 00086 X( I, J ) = 0.0 00087 10 CONTINUE 00088 20 CONTINUE 00089 N5 = N / 5 00090 N5 = N - 5*N5 + 1 00091 * 00092 DO 30 I = N, N5, -5 00093 A = ALPHA3*CLARND( 5, ISEED ) 00094 B = CLARND( 5, ISEED ) / ALPHA 00095 C = A - 2.*B*EYE 00096 R = C / BETA 00097 X( I, I ) = A 00098 X( I-2, I ) = B 00099 X( I-2, I-1 ) = R 00100 X( I-2, I-2 ) = C 00101 X( I-1, I-1 ) = CLARND( 2, ISEED ) 00102 X( I-3, I-3 ) = CLARND( 2, ISEED ) 00103 X( I-4, I-4 ) = CLARND( 2, ISEED ) 00104 IF( ABS( X( I-3, I-3 ) ).GT.ABS( X( I-4, I-4 ) ) ) THEN 00105 X( I-4, I-3 ) = 2.0*X( I-3, I-3 ) 00106 ELSE 00107 X( I-4, I-3 ) = 2.0*X( I-4, I-4 ) 00108 END IF 00109 30 CONTINUE 00110 * 00111 * Clean-up for N not a multiple of 5. 00112 * 00113 I = N5 - 1 00114 IF( I.GT.2 ) THEN 00115 A = ALPHA3*CLARND( 5, ISEED ) 00116 B = CLARND( 5, ISEED ) / ALPHA 00117 C = A - 2.*B*EYE 00118 R = C / BETA 00119 X( I, I ) = A 00120 X( I-2, I ) = B 00121 X( I-2, I-1 ) = R 00122 X( I-2, I-2 ) = C 00123 X( I-1, I-1 ) = CLARND( 2, ISEED ) 00124 I = I - 3 00125 END IF 00126 IF( I.GT.1 ) THEN 00127 X( I, I ) = CLARND( 2, ISEED ) 00128 X( I-1, I-1 ) = CLARND( 2, ISEED ) 00129 IF( ABS( X( I, I ) ).GT.ABS( X( I-1, I-1 ) ) ) THEN 00130 X( I-1, I ) = 2.0*X( I, I ) 00131 ELSE 00132 X( I-1, I ) = 2.0*X( I-1, I-1 ) 00133 END IF 00134 I = I - 2 00135 ELSE IF( I.EQ.1 ) THEN 00136 X( I, I ) = CLARND( 2, ISEED ) 00137 I = I - 1 00138 END IF 00139 * 00140 * UPLO = 'L': Lower triangular storage 00141 * 00142 ELSE 00143 * 00144 * Fill the lower triangle of the matrix with zeros. 00145 * 00146 DO 50 J = 1, N 00147 DO 40 I = J, N 00148 X( I, J ) = 0.0 00149 40 CONTINUE 00150 50 CONTINUE 00151 N5 = N / 5 00152 N5 = N5*5 00153 * 00154 DO 60 I = 1, N5, 5 00155 A = ALPHA3*CLARND( 5, ISEED ) 00156 B = CLARND( 5, ISEED ) / ALPHA 00157 C = A - 2.*B*EYE 00158 R = C / BETA 00159 X( I, I ) = A 00160 X( I+2, I ) = B 00161 X( I+2, I+1 ) = R 00162 X( I+2, I+2 ) = C 00163 X( I+1, I+1 ) = CLARND( 2, ISEED ) 00164 X( I+3, I+3 ) = CLARND( 2, ISEED ) 00165 X( I+4, I+4 ) = CLARND( 2, ISEED ) 00166 IF( ABS( X( I+3, I+3 ) ).GT.ABS( X( I+4, I+4 ) ) ) THEN 00167 X( I+4, I+3 ) = 2.0*X( I+3, I+3 ) 00168 ELSE 00169 X( I+4, I+3 ) = 2.0*X( I+4, I+4 ) 00170 END IF 00171 60 CONTINUE 00172 * 00173 * Clean-up for N not a multiple of 5. 00174 * 00175 I = N5 + 1 00176 IF( I.LT.N-1 ) THEN 00177 A = ALPHA3*CLARND( 5, ISEED ) 00178 B = CLARND( 5, ISEED ) / ALPHA 00179 C = A - 2.*B*EYE 00180 R = C / BETA 00181 X( I, I ) = A 00182 X( I+2, I ) = B 00183 X( I+2, I+1 ) = R 00184 X( I+2, I+2 ) = C 00185 X( I+1, I+1 ) = CLARND( 2, ISEED ) 00186 I = I + 3 00187 END IF 00188 IF( I.LT.N ) THEN 00189 X( I, I ) = CLARND( 2, ISEED ) 00190 X( I+1, I+1 ) = CLARND( 2, ISEED ) 00191 IF( ABS( X( I, I ) ).GT.ABS( X( I+1, I+1 ) ) ) THEN 00192 X( I+1, I ) = 2.0*X( I, I ) 00193 ELSE 00194 X( I+1, I ) = 2.0*X( I+1, I+1 ) 00195 END IF 00196 I = I + 2 00197 ELSE IF( I.EQ.N ) THEN 00198 X( I, I ) = CLARND( 2, ISEED ) 00199 I = I + 1 00200 END IF 00201 END IF 00202 * 00203 RETURN 00204 * 00205 * End of CLATSY 00206 * 00207 END
1.7.3 
