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LAPACK 3.3.0
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LAPACK 3.3.0
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00001 SUBROUTINE CHPMV(UPLO,N,ALPHA,AP,X,INCX,BETA,Y,INCY) 00002 * .. Scalar Arguments .. 00003 COMPLEX ALPHA,BETA 00004 INTEGER INCX,INCY,N 00005 CHARACTER UPLO 00006 * .. 00007 * .. Array Arguments .. 00008 COMPLEX AP(*),X(*),Y(*) 00009 * .. 00010 * 00011 * Purpose 00012 * ======= 00013 * 00014 * CHPMV performs the matrix-vector operation 00015 * 00016 * y := alpha*A*x + beta*y, 00017 * 00018 * where alpha and beta are scalars, x and y are n element vectors and 00019 * A is an n by n hermitian matrix, supplied in packed form. 00020 * 00021 * Arguments 00022 * ========== 00023 * 00024 * UPLO - CHARACTER*1. 00025 * On entry, UPLO specifies whether the upper or lower 00026 * triangular part of the matrix A is supplied in the packed 00027 * array AP as follows: 00028 * 00029 * UPLO = 'U' or 'u' The upper triangular part of A is 00030 * supplied in AP. 00031 * 00032 * UPLO = 'L' or 'l' The lower triangular part of A is 00033 * supplied in AP. 00034 * 00035 * Unchanged on exit. 00036 * 00037 * N - INTEGER. 00038 * On entry, N specifies the order of the matrix A. 00039 * N must be at least zero. 00040 * Unchanged on exit. 00041 * 00042 * ALPHA - COMPLEX . 00043 * On entry, ALPHA specifies the scalar alpha. 00044 * Unchanged on exit. 00045 * 00046 * AP - COMPLEX array of DIMENSION at least 00047 * ( ( n*( n + 1 ) )/2 ). 00048 * Before entry with UPLO = 'U' or 'u', the array AP must 00049 * contain the upper triangular part of the hermitian matrix 00050 * packed sequentially, column by column, so that AP( 1 ) 00051 * contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 ) 00052 * and a( 2, 2 ) respectively, and so on. 00053 * Before entry with UPLO = 'L' or 'l', the array AP must 00054 * contain the lower triangular part of the hermitian matrix 00055 * packed sequentially, column by column, so that AP( 1 ) 00056 * contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 ) 00057 * and a( 3, 1 ) respectively, and so on. 00058 * Note that the imaginary parts of the diagonal elements need 00059 * not be set and are assumed to be zero. 00060 * Unchanged on exit. 00061 * 00062 * X - COMPLEX array of dimension at least 00063 * ( 1 + ( n - 1 )*abs( INCX ) ). 00064 * Before entry, the incremented array X must contain the n 00065 * element vector x. 00066 * Unchanged on exit. 00067 * 00068 * INCX - INTEGER. 00069 * On entry, INCX specifies the increment for the elements of 00070 * X. INCX must not be zero. 00071 * Unchanged on exit. 00072 * 00073 * BETA - COMPLEX . 00074 * On entry, BETA specifies the scalar beta. When BETA is 00075 * supplied as zero then Y need not be set on input. 00076 * Unchanged on exit. 00077 * 00078 * Y - COMPLEX array of dimension at least 00079 * ( 1 + ( n - 1 )*abs( INCY ) ). 00080 * Before entry, the incremented array Y must contain the n 00081 * element vector y. On exit, Y is overwritten by the updated 00082 * vector y. 00083 * 00084 * INCY - INTEGER. 00085 * On entry, INCY specifies the increment for the elements of 00086 * Y. INCY must not be zero. 00087 * Unchanged on exit. 00088 * 00089 * Further Details 00090 * =============== 00091 * 00092 * Level 2 Blas routine. 00093 * 00094 * -- Written on 22-October-1986. 00095 * Jack Dongarra, Argonne National Lab. 00096 * Jeremy Du Croz, Nag Central Office. 00097 * Sven Hammarling, Nag Central Office. 00098 * Richard Hanson, Sandia National Labs. 00099 * 00100 * ===================================================================== 00101 * 00102 * .. Parameters .. 00103 COMPLEX ONE 00104 PARAMETER (ONE= (1.0E+0,0.0E+0)) 00105 COMPLEX ZERO 00106 PARAMETER (ZERO= (0.0E+0,0.0E+0)) 00107 * .. 00108 * .. Local Scalars .. 00109 COMPLEX TEMP1,TEMP2 00110 INTEGER I,INFO,IX,IY,J,JX,JY,K,KK,KX,KY 00111 * .. 00112 * .. External Functions .. 00113 LOGICAL LSAME 00114 EXTERNAL LSAME 00115 * .. 00116 * .. External Subroutines .. 00117 EXTERNAL XERBLA 00118 * .. 00119 * .. Intrinsic Functions .. 00120 INTRINSIC CONJG,REAL 00121 * .. 00122 * 00123 * Test the input parameters. 00124 * 00125 INFO = 0 00126 IF (.NOT.LSAME(UPLO,'U') .AND. .NOT.LSAME(UPLO,'L')) THEN 00127 INFO = 1 00128 ELSE IF (N.LT.0) THEN 00129 INFO = 2 00130 ELSE IF (INCX.EQ.0) THEN 00131 INFO = 6 00132 ELSE IF (INCY.EQ.0) THEN 00133 INFO = 9 00134 END IF 00135 IF (INFO.NE.0) THEN 00136 CALL XERBLA('CHPMV ',INFO) 00137 RETURN 00138 END IF 00139 * 00140 * Quick return if possible. 00141 * 00142 IF ((N.EQ.0) .OR. ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN 00143 * 00144 * Set up the start points in X and Y. 00145 * 00146 IF (INCX.GT.0) THEN 00147 KX = 1 00148 ELSE 00149 KX = 1 - (N-1)*INCX 00150 END IF 00151 IF (INCY.GT.0) THEN 00152 KY = 1 00153 ELSE 00154 KY = 1 - (N-1)*INCY 00155 END IF 00156 * 00157 * Start the operations. In this version the elements of the array AP 00158 * are accessed sequentially with one pass through AP. 00159 * 00160 * First form y := beta*y. 00161 * 00162 IF (BETA.NE.ONE) THEN 00163 IF (INCY.EQ.1) THEN 00164 IF (BETA.EQ.ZERO) THEN 00165 DO 10 I = 1,N 00166 Y(I) = ZERO 00167 10 CONTINUE 00168 ELSE 00169 DO 20 I = 1,N 00170 Y(I) = BETA*Y(I) 00171 20 CONTINUE 00172 END IF 00173 ELSE 00174 IY = KY 00175 IF (BETA.EQ.ZERO) THEN 00176 DO 30 I = 1,N 00177 Y(IY) = ZERO 00178 IY = IY + INCY 00179 30 CONTINUE 00180 ELSE 00181 DO 40 I = 1,N 00182 Y(IY) = BETA*Y(IY) 00183 IY = IY + INCY 00184 40 CONTINUE 00185 END IF 00186 END IF 00187 END IF 00188 IF (ALPHA.EQ.ZERO) RETURN 00189 KK = 1 00190 IF (LSAME(UPLO,'U')) THEN 00191 * 00192 * Form y when AP contains the upper triangle. 00193 * 00194 IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN 00195 DO 60 J = 1,N 00196 TEMP1 = ALPHA*X(J) 00197 TEMP2 = ZERO 00198 K = KK 00199 DO 50 I = 1,J - 1 00200 Y(I) = Y(I) + TEMP1*AP(K) 00201 TEMP2 = TEMP2 + CONJG(AP(K))*X(I) 00202 K = K + 1 00203 50 CONTINUE 00204 Y(J) = Y(J) + TEMP1*REAL(AP(KK+J-1)) + ALPHA*TEMP2 00205 KK = KK + J 00206 60 CONTINUE 00207 ELSE 00208 JX = KX 00209 JY = KY 00210 DO 80 J = 1,N 00211 TEMP1 = ALPHA*X(JX) 00212 TEMP2 = ZERO 00213 IX = KX 00214 IY = KY 00215 DO 70 K = KK,KK + J - 2 00216 Y(IY) = Y(IY) + TEMP1*AP(K) 00217 TEMP2 = TEMP2 + CONJG(AP(K))*X(IX) 00218 IX = IX + INCX 00219 IY = IY + INCY 00220 70 CONTINUE 00221 Y(JY) = Y(JY) + TEMP1*REAL(AP(KK+J-1)) + ALPHA*TEMP2 00222 JX = JX + INCX 00223 JY = JY + INCY 00224 KK = KK + J 00225 80 CONTINUE 00226 END IF 00227 ELSE 00228 * 00229 * Form y when AP contains the lower triangle. 00230 * 00231 IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN 00232 DO 100 J = 1,N 00233 TEMP1 = ALPHA*X(J) 00234 TEMP2 = ZERO 00235 Y(J) = Y(J) + TEMP1*REAL(AP(KK)) 00236 K = KK + 1 00237 DO 90 I = J + 1,N 00238 Y(I) = Y(I) + TEMP1*AP(K) 00239 TEMP2 = TEMP2 + CONJG(AP(K))*X(I) 00240 K = K + 1 00241 90 CONTINUE 00242 Y(J) = Y(J) + ALPHA*TEMP2 00243 KK = KK + (N-J+1) 00244 100 CONTINUE 00245 ELSE 00246 JX = KX 00247 JY = KY 00248 DO 120 J = 1,N 00249 TEMP1 = ALPHA*X(JX) 00250 TEMP2 = ZERO 00251 Y(JY) = Y(JY) + TEMP1*REAL(AP(KK)) 00252 IX = JX 00253 IY = JY 00254 DO 110 K = KK + 1,KK + N - J 00255 IX = IX + INCX 00256 IY = IY + INCY 00257 Y(IY) = Y(IY) + TEMP1*AP(K) 00258 TEMP2 = TEMP2 + CONJG(AP(K))*X(IX) 00259 110 CONTINUE 00260 Y(JY) = Y(JY) + ALPHA*TEMP2 00261 JX = JX + INCX 00262 JY = JY + INCY 00263 KK = KK + (N-J+1) 00264 120 CONTINUE 00265 END IF 00266 END IF 00267 * 00268 RETURN 00269 * 00270 * End of CHPMV . 00271 * 00272 END
1.7.3 
