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8692
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1 SUBROUTINE CHEMM(SIDE,UPLO,M,N,ALPHA,A,LDA,B,LDB,BETA,C,LDC) |
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2 * .. Scalar Arguments .. |
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3 COMPLEX ALPHA,BETA |
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4 INTEGER LDA,LDB,LDC,M,N |
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5 CHARACTER SIDE,UPLO |
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6 * .. |
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7 * .. Array Arguments .. |
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8 COMPLEX A(LDA,*),B(LDB,*),C(LDC,*) |
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9 * .. |
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10 * |
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11 * Purpose |
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12 * ======= |
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13 * |
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14 * CHEMM performs one of the matrix-matrix operations |
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15 * |
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16 * C := alpha*A*B + beta*C, |
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17 * |
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18 * or |
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19 * |
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20 * C := alpha*B*A + beta*C, |
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21 * |
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22 * where alpha and beta are scalars, A is an hermitian matrix and B and |
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23 * C are m by n matrices. |
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24 * |
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25 * Arguments |
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26 * ========== |
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27 * |
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28 * SIDE - CHARACTER*1. |
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29 * On entry, SIDE specifies whether the hermitian matrix A |
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30 * appears on the left or right in the operation as follows: |
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31 * |
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32 * SIDE = 'L' or 'l' C := alpha*A*B + beta*C, |
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33 * |
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34 * SIDE = 'R' or 'r' C := alpha*B*A + beta*C, |
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35 * |
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36 * Unchanged on exit. |
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37 * |
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38 * UPLO - CHARACTER*1. |
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39 * On entry, UPLO specifies whether the upper or lower |
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40 * triangular part of the hermitian matrix A is to be |
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41 * referenced as follows: |
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42 * |
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43 * UPLO = 'U' or 'u' Only the upper triangular part of the |
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44 * hermitian matrix is to be referenced. |
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45 * |
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46 * UPLO = 'L' or 'l' Only the lower triangular part of the |
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47 * hermitian matrix is to be referenced. |
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48 * |
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49 * Unchanged on exit. |
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50 * |
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51 * M - INTEGER. |
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52 * On entry, M specifies the number of rows of the matrix C. |
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53 * M must be at least zero. |
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54 * Unchanged on exit. |
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55 * |
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56 * N - INTEGER. |
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57 * On entry, N specifies the number of columns of the matrix C. |
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58 * N must be at least zero. |
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59 * Unchanged on exit. |
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60 * |
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61 * ALPHA - COMPLEX . |
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62 * On entry, ALPHA specifies the scalar alpha. |
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63 * Unchanged on exit. |
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64 * |
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65 * A - COMPLEX array of DIMENSION ( LDA, ka ), where ka is |
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66 * m when SIDE = 'L' or 'l' and is n otherwise. |
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67 * Before entry with SIDE = 'L' or 'l', the m by m part of |
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68 * the array A must contain the hermitian matrix, such that |
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69 * when UPLO = 'U' or 'u', the leading m by m upper triangular |
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70 * part of the array A must contain the upper triangular part |
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71 * of the hermitian matrix and the strictly lower triangular |
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72 * part of A is not referenced, and when UPLO = 'L' or 'l', |
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73 * the leading m by m lower triangular part of the array A |
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74 * must contain the lower triangular part of the hermitian |
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75 * matrix and the strictly upper triangular part of A is not |
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76 * referenced. |
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77 * Before entry with SIDE = 'R' or 'r', the n by n part of |
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78 * the array A must contain the hermitian matrix, such that |
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79 * when UPLO = 'U' or 'u', the leading n by n upper triangular |
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80 * part of the array A must contain the upper triangular part |
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81 * of the hermitian matrix and the strictly lower triangular |
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82 * part of A is not referenced, and when UPLO = 'L' or 'l', |
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83 * the leading n by n lower triangular part of the array A |
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84 * must contain the lower triangular part of the hermitian |
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85 * matrix and the strictly upper triangular part of A is not |
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86 * referenced. |
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87 * Note that the imaginary parts of the diagonal elements need |
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88 * not be set, they are assumed to be zero. |
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89 * Unchanged on exit. |
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90 * |
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91 * LDA - INTEGER. |
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92 * On entry, LDA specifies the first dimension of A as declared |
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93 * in the calling (sub) program. When SIDE = 'L' or 'l' then |
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94 * LDA must be at least max( 1, m ), otherwise LDA must be at |
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95 * least max( 1, n ). |
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96 * Unchanged on exit. |
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97 * |
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98 * B - COMPLEX array of DIMENSION ( LDB, n ). |
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99 * Before entry, the leading m by n part of the array B must |
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100 * contain the matrix B. |
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101 * Unchanged on exit. |
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102 * |
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103 * LDB - INTEGER. |
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104 * On entry, LDB specifies the first dimension of B as declared |
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105 * in the calling (sub) program. LDB must be at least |
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106 * max( 1, m ). |
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107 * Unchanged on exit. |
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108 * |
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109 * BETA - COMPLEX . |
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110 * On entry, BETA specifies the scalar beta. When BETA is |
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111 * supplied as zero then C need not be set on input. |
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112 * Unchanged on exit. |
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113 * |
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114 * C - COMPLEX array of DIMENSION ( LDC, n ). |
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115 * Before entry, the leading m by n part of the array C must |
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116 * contain the matrix C, except when beta is zero, in which |
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117 * case C need not be set on entry. |
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118 * On exit, the array C is overwritten by the m by n updated |
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119 * matrix. |
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120 * |
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121 * LDC - INTEGER. |
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122 * On entry, LDC specifies the first dimension of C as declared |
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123 * in the calling (sub) program. LDC must be at least |
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124 * max( 1, m ). |
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125 * Unchanged on exit. |
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126 * |
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127 * |
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128 * Level 3 Blas routine. |
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129 * |
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130 * -- Written on 8-February-1989. |
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131 * Jack Dongarra, Argonne National Laboratory. |
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132 * Iain Duff, AERE Harwell. |
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133 * Jeremy Du Croz, Numerical Algorithms Group Ltd. |
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134 * Sven Hammarling, Numerical Algorithms Group Ltd. |
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135 * |
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136 * |
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137 * .. External Functions .. |
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138 LOGICAL LSAME |
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139 EXTERNAL LSAME |
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140 * .. |
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141 * .. External Subroutines .. |
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142 EXTERNAL XERBLA |
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143 * .. |
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144 * .. Intrinsic Functions .. |
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145 INTRINSIC CONJG,MAX,REAL |
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146 * .. |
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147 * .. Local Scalars .. |
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148 COMPLEX TEMP1,TEMP2 |
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149 INTEGER I,INFO,J,K,NROWA |
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150 LOGICAL UPPER |
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151 * .. |
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152 * .. Parameters .. |
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153 COMPLEX ONE |
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154 PARAMETER (ONE= (1.0E+0,0.0E+0)) |
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155 COMPLEX ZERO |
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156 PARAMETER (ZERO= (0.0E+0,0.0E+0)) |
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157 * .. |
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158 * |
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159 * Set NROWA as the number of rows of A. |
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160 * |
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161 IF (LSAME(SIDE,'L')) THEN |
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162 NROWA = M |
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163 ELSE |
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164 NROWA = N |
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165 END IF |
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166 UPPER = LSAME(UPLO,'U') |
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167 * |
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168 * Test the input parameters. |
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169 * |
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170 INFO = 0 |
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171 IF ((.NOT.LSAME(SIDE,'L')) .AND. (.NOT.LSAME(SIDE,'R'))) THEN |
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172 INFO = 1 |
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173 ELSE IF ((.NOT.UPPER) .AND. (.NOT.LSAME(UPLO,'L'))) THEN |
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174 INFO = 2 |
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175 ELSE IF (M.LT.0) THEN |
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176 INFO = 3 |
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177 ELSE IF (N.LT.0) THEN |
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178 INFO = 4 |
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179 ELSE IF (LDA.LT.MAX(1,NROWA)) THEN |
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180 INFO = 7 |
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181 ELSE IF (LDB.LT.MAX(1,M)) THEN |
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182 INFO = 9 |
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183 ELSE IF (LDC.LT.MAX(1,M)) THEN |
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184 INFO = 12 |
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185 END IF |
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186 IF (INFO.NE.0) THEN |
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187 CALL XERBLA('CHEMM ',INFO) |
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188 RETURN |
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189 END IF |
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190 * |
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191 * Quick return if possible. |
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192 * |
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193 IF ((M.EQ.0) .OR. (N.EQ.0) .OR. |
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194 + ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN |
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195 * |
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196 * And when alpha.eq.zero. |
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197 * |
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198 IF (ALPHA.EQ.ZERO) THEN |
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199 IF (BETA.EQ.ZERO) THEN |
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200 DO 20 J = 1,N |
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201 DO 10 I = 1,M |
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202 C(I,J) = ZERO |
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203 10 CONTINUE |
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204 20 CONTINUE |
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205 ELSE |
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206 DO 40 J = 1,N |
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207 DO 30 I = 1,M |
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208 C(I,J) = BETA*C(I,J) |
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209 30 CONTINUE |
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210 40 CONTINUE |
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211 END IF |
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212 RETURN |
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213 END IF |
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214 * |
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215 * Start the operations. |
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216 * |
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217 IF (LSAME(SIDE,'L')) THEN |
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218 * |
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219 * Form C := alpha*A*B + beta*C. |
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220 * |
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221 IF (UPPER) THEN |
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222 DO 70 J = 1,N |
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223 DO 60 I = 1,M |
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224 TEMP1 = ALPHA*B(I,J) |
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225 TEMP2 = ZERO |
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226 DO 50 K = 1,I - 1 |
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227 C(K,J) = C(K,J) + TEMP1*A(K,I) |
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228 TEMP2 = TEMP2 + B(K,J)*CONJG(A(K,I)) |
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229 50 CONTINUE |
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230 IF (BETA.EQ.ZERO) THEN |
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231 C(I,J) = TEMP1*REAL(A(I,I)) + ALPHA*TEMP2 |
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232 ELSE |
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233 C(I,J) = BETA*C(I,J) + TEMP1*REAL(A(I,I)) + |
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234 + ALPHA*TEMP2 |
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235 END IF |
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236 60 CONTINUE |
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237 70 CONTINUE |
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238 ELSE |
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239 DO 100 J = 1,N |
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240 DO 90 I = M,1,-1 |
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241 TEMP1 = ALPHA*B(I,J) |
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242 TEMP2 = ZERO |
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243 DO 80 K = I + 1,M |
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244 C(K,J) = C(K,J) + TEMP1*A(K,I) |
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245 TEMP2 = TEMP2 + B(K,J)*CONJG(A(K,I)) |
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246 80 CONTINUE |
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247 IF (BETA.EQ.ZERO) THEN |
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248 C(I,J) = TEMP1*REAL(A(I,I)) + ALPHA*TEMP2 |
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249 ELSE |
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250 C(I,J) = BETA*C(I,J) + TEMP1*REAL(A(I,I)) + |
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251 + ALPHA*TEMP2 |
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252 END IF |
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253 90 CONTINUE |
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254 100 CONTINUE |
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255 END IF |
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256 ELSE |
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257 * |
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258 * Form C := alpha*B*A + beta*C. |
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259 * |
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260 DO 170 J = 1,N |
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261 TEMP1 = ALPHA*REAL(A(J,J)) |
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262 IF (BETA.EQ.ZERO) THEN |
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263 DO 110 I = 1,M |
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264 C(I,J) = TEMP1*B(I,J) |
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265 110 CONTINUE |
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266 ELSE |
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267 DO 120 I = 1,M |
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268 C(I,J) = BETA*C(I,J) + TEMP1*B(I,J) |
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269 120 CONTINUE |
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270 END IF |
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271 DO 140 K = 1,J - 1 |
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272 IF (UPPER) THEN |
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273 TEMP1 = ALPHA*A(K,J) |
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274 ELSE |
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275 TEMP1 = ALPHA*CONJG(A(J,K)) |
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276 END IF |
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277 DO 130 I = 1,M |
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278 C(I,J) = C(I,J) + TEMP1*B(I,K) |
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279 130 CONTINUE |
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280 140 CONTINUE |
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281 DO 160 K = J + 1,N |
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282 IF (UPPER) THEN |
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283 TEMP1 = ALPHA*CONJG(A(J,K)) |
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284 ELSE |
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285 TEMP1 = ALPHA*A(K,J) |
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286 END IF |
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287 DO 150 I = 1,M |
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288 C(I,J) = C(I,J) + TEMP1*B(I,K) |
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289 150 CONTINUE |
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290 160 CONTINUE |
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291 170 CONTINUE |
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292 END IF |
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293 * |
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294 RETURN |
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295 * |
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296 * End of CHEMM . |
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297 * |
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298 END |
