Annotation of rpl/lapack/blas/dgemm.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE DGEMM(TRANSA,TRANSB,M,N,K,ALPHA,A,LDA,B,LDB,BETA,C,LDC)
! 2: * .. Scalar Arguments ..
! 3: DOUBLE PRECISION ALPHA,BETA
! 4: INTEGER K,LDA,LDB,LDC,M,N
! 5: CHARACTER TRANSA,TRANSB
! 6: * ..
! 7: * .. Array Arguments ..
! 8: DOUBLE PRECISION A(LDA,*),B(LDB,*),C(LDC,*)
! 9: * ..
! 10: *
! 11: * Purpose
! 12: * =======
! 13: *
! 14: * DGEMM performs one of the matrix-matrix operations
! 15: *
! 16: * C := alpha*op( A )*op( B ) + beta*C,
! 17: *
! 18: * where op( X ) is one of
! 19: *
! 20: * op( X ) = X or op( X ) = X',
! 21: *
! 22: * alpha and beta are scalars, and A, B and C are matrices, with op( A )
! 23: * an m by k matrix, op( B ) a k by n matrix and C an m by n matrix.
! 24: *
! 25: * Arguments
! 26: * ==========
! 27: *
! 28: * TRANSA - CHARACTER*1.
! 29: * On entry, TRANSA specifies the form of op( A ) to be used in
! 30: * the matrix multiplication as follows:
! 31: *
! 32: * TRANSA = 'N' or 'n', op( A ) = A.
! 33: *
! 34: * TRANSA = 'T' or 't', op( A ) = A'.
! 35: *
! 36: * TRANSA = 'C' or 'c', op( A ) = A'.
! 37: *
! 38: * Unchanged on exit.
! 39: *
! 40: * TRANSB - CHARACTER*1.
! 41: * On entry, TRANSB specifies the form of op( B ) to be used in
! 42: * the matrix multiplication as follows:
! 43: *
! 44: * TRANSB = 'N' or 'n', op( B ) = B.
! 45: *
! 46: * TRANSB = 'T' or 't', op( B ) = B'.
! 47: *
! 48: * TRANSB = 'C' or 'c', op( B ) = B'.
! 49: *
! 50: * Unchanged on exit.
! 51: *
! 52: * M - INTEGER.
! 53: * On entry, M specifies the number of rows of the matrix
! 54: * op( A ) and of the matrix C. M must be at least zero.
! 55: * Unchanged on exit.
! 56: *
! 57: * N - INTEGER.
! 58: * On entry, N specifies the number of columns of the matrix
! 59: * op( B ) and the number of columns of the matrix C. N must be
! 60: * at least zero.
! 61: * Unchanged on exit.
! 62: *
! 63: * K - INTEGER.
! 64: * On entry, K specifies the number of columns of the matrix
! 65: * op( A ) and the number of rows of the matrix op( B ). K must
! 66: * be at least zero.
! 67: * Unchanged on exit.
! 68: *
! 69: * ALPHA - DOUBLE PRECISION.
! 70: * On entry, ALPHA specifies the scalar alpha.
! 71: * Unchanged on exit.
! 72: *
! 73: * A - DOUBLE PRECISION array of DIMENSION ( LDA, ka ), where ka is
! 74: * k when TRANSA = 'N' or 'n', and is m otherwise.
! 75: * Before entry with TRANSA = 'N' or 'n', the leading m by k
! 76: * part of the array A must contain the matrix A, otherwise
! 77: * the leading k by m part of the array A must contain the
! 78: * matrix A.
! 79: * Unchanged on exit.
! 80: *
! 81: * LDA - INTEGER.
! 82: * On entry, LDA specifies the first dimension of A as declared
! 83: * in the calling (sub) program. When TRANSA = 'N' or 'n' then
! 84: * LDA must be at least max( 1, m ), otherwise LDA must be at
! 85: * least max( 1, k ).
! 86: * Unchanged on exit.
! 87: *
! 88: * B - DOUBLE PRECISION array of DIMENSION ( LDB, kb ), where kb is
! 89: * n when TRANSB = 'N' or 'n', and is k otherwise.
! 90: * Before entry with TRANSB = 'N' or 'n', the leading k by n
! 91: * part of the array B must contain the matrix B, otherwise
! 92: * the leading n by k part of the array B must contain the
! 93: * matrix B.
! 94: * Unchanged on exit.
! 95: *
! 96: * LDB - INTEGER.
! 97: * On entry, LDB specifies the first dimension of B as declared
! 98: * in the calling (sub) program. When TRANSB = 'N' or 'n' then
! 99: * LDB must be at least max( 1, k ), otherwise LDB must be at
! 100: * least max( 1, n ).
! 101: * Unchanged on exit.
! 102: *
! 103: * BETA - DOUBLE PRECISION.
! 104: * On entry, BETA specifies the scalar beta. When BETA is
! 105: * supplied as zero then C need not be set on input.
! 106: * Unchanged on exit.
! 107: *
! 108: * C - DOUBLE PRECISION array of DIMENSION ( LDC, n ).
! 109: * Before entry, the leading m by n part of the array C must
! 110: * contain the matrix C, except when beta is zero, in which
! 111: * case C need not be set on entry.
! 112: * On exit, the array C is overwritten by the m by n matrix
! 113: * ( alpha*op( A )*op( B ) + beta*C ).
! 114: *
! 115: * LDC - INTEGER.
! 116: * On entry, LDC specifies the first dimension of C as declared
! 117: * in the calling (sub) program. LDC must be at least
! 118: * max( 1, m ).
! 119: * Unchanged on exit.
! 120: *
! 121: * Further Details
! 122: * ===============
! 123: *
! 124: * Level 3 Blas routine.
! 125: *
! 126: * -- Written on 8-February-1989.
! 127: * Jack Dongarra, Argonne National Laboratory.
! 128: * Iain Duff, AERE Harwell.
! 129: * Jeremy Du Croz, Numerical Algorithms Group Ltd.
! 130: * Sven Hammarling, Numerical Algorithms Group Ltd.
! 131: *
! 132: * =====================================================================
! 133: *
! 134: * .. External Functions ..
! 135: LOGICAL LSAME
! 136: EXTERNAL LSAME
! 137: * ..
! 138: * .. External Subroutines ..
! 139: EXTERNAL XERBLA
! 140: * ..
! 141: * .. Intrinsic Functions ..
! 142: INTRINSIC MAX
! 143: * ..
! 144: * .. Local Scalars ..
! 145: DOUBLE PRECISION TEMP
! 146: INTEGER I,INFO,J,L,NCOLA,NROWA,NROWB
! 147: LOGICAL NOTA,NOTB
! 148: * ..
! 149: * .. Parameters ..
! 150: DOUBLE PRECISION ONE,ZERO
! 151: PARAMETER (ONE=1.0D+0,ZERO=0.0D+0)
! 152: * ..
! 153: *
! 154: * Set NOTA and NOTB as true if A and B respectively are not
! 155: * transposed and set NROWA, NCOLA and NROWB as the number of rows
! 156: * and columns of A and the number of rows of B respectively.
! 157: *
! 158: NOTA = LSAME(TRANSA,'N')
! 159: NOTB = LSAME(TRANSB,'N')
! 160: IF (NOTA) THEN
! 161: NROWA = M
! 162: NCOLA = K
! 163: ELSE
! 164: NROWA = K
! 165: NCOLA = M
! 166: END IF
! 167: IF (NOTB) THEN
! 168: NROWB = K
! 169: ELSE
! 170: NROWB = N
! 171: END IF
! 172: *
! 173: * Test the input parameters.
! 174: *
! 175: INFO = 0
! 176: IF ((.NOT.NOTA) .AND. (.NOT.LSAME(TRANSA,'C')) .AND.
! 177: + (.NOT.LSAME(TRANSA,'T'))) THEN
! 178: INFO = 1
! 179: ELSE IF ((.NOT.NOTB) .AND. (.NOT.LSAME(TRANSB,'C')) .AND.
! 180: + (.NOT.LSAME(TRANSB,'T'))) THEN
! 181: INFO = 2
! 182: ELSE IF (M.LT.0) THEN
! 183: INFO = 3
! 184: ELSE IF (N.LT.0) THEN
! 185: INFO = 4
! 186: ELSE IF (K.LT.0) THEN
! 187: INFO = 5
! 188: ELSE IF (LDA.LT.MAX(1,NROWA)) THEN
! 189: INFO = 8
! 190: ELSE IF (LDB.LT.MAX(1,NROWB)) THEN
! 191: INFO = 10
! 192: ELSE IF (LDC.LT.MAX(1,M)) THEN
! 193: INFO = 13
! 194: END IF
! 195: IF (INFO.NE.0) THEN
! 196: CALL XERBLA('DGEMM ',INFO)
! 197: RETURN
! 198: END IF
! 199: *
! 200: * Quick return if possible.
! 201: *
! 202: IF ((M.EQ.0) .OR. (N.EQ.0) .OR.
! 203: + (((ALPHA.EQ.ZERO).OR. (K.EQ.0)).AND. (BETA.EQ.ONE))) RETURN
! 204: *
! 205: * And if alpha.eq.zero.
! 206: *
! 207: IF (ALPHA.EQ.ZERO) THEN
! 208: IF (BETA.EQ.ZERO) THEN
! 209: DO 20 J = 1,N
! 210: DO 10 I = 1,M
! 211: C(I,J) = ZERO
! 212: 10 CONTINUE
! 213: 20 CONTINUE
! 214: ELSE
! 215: DO 40 J = 1,N
! 216: DO 30 I = 1,M
! 217: C(I,J) = BETA*C(I,J)
! 218: 30 CONTINUE
! 219: 40 CONTINUE
! 220: END IF
! 221: RETURN
! 222: END IF
! 223: *
! 224: * Start the operations.
! 225: *
! 226: IF (NOTB) THEN
! 227: IF (NOTA) THEN
! 228: *
! 229: * Form C := alpha*A*B + beta*C.
! 230: *
! 231: DO 90 J = 1,N
! 232: IF (BETA.EQ.ZERO) THEN
! 233: DO 50 I = 1,M
! 234: C(I,J) = ZERO
! 235: 50 CONTINUE
! 236: ELSE IF (BETA.NE.ONE) THEN
! 237: DO 60 I = 1,M
! 238: C(I,J) = BETA*C(I,J)
! 239: 60 CONTINUE
! 240: END IF
! 241: DO 80 L = 1,K
! 242: IF (B(L,J).NE.ZERO) THEN
! 243: TEMP = ALPHA*B(L,J)
! 244: DO 70 I = 1,M
! 245: C(I,J) = C(I,J) + TEMP*A(I,L)
! 246: 70 CONTINUE
! 247: END IF
! 248: 80 CONTINUE
! 249: 90 CONTINUE
! 250: ELSE
! 251: *
! 252: * Form C := alpha*A'*B + beta*C
! 253: *
! 254: DO 120 J = 1,N
! 255: DO 110 I = 1,M
! 256: TEMP = ZERO
! 257: DO 100 L = 1,K
! 258: TEMP = TEMP + A(L,I)*B(L,J)
! 259: 100 CONTINUE
! 260: IF (BETA.EQ.ZERO) THEN
! 261: C(I,J) = ALPHA*TEMP
! 262: ELSE
! 263: C(I,J) = ALPHA*TEMP + BETA*C(I,J)
! 264: END IF
! 265: 110 CONTINUE
! 266: 120 CONTINUE
! 267: END IF
! 268: ELSE
! 269: IF (NOTA) THEN
! 270: *
! 271: * Form C := alpha*A*B' + beta*C
! 272: *
! 273: DO 170 J = 1,N
! 274: IF (BETA.EQ.ZERO) THEN
! 275: DO 130 I = 1,M
! 276: C(I,J) = ZERO
! 277: 130 CONTINUE
! 278: ELSE IF (BETA.NE.ONE) THEN
! 279: DO 140 I = 1,M
! 280: C(I,J) = BETA*C(I,J)
! 281: 140 CONTINUE
! 282: END IF
! 283: DO 160 L = 1,K
! 284: IF (B(J,L).NE.ZERO) THEN
! 285: TEMP = ALPHA*B(J,L)
! 286: DO 150 I = 1,M
! 287: C(I,J) = C(I,J) + TEMP*A(I,L)
! 288: 150 CONTINUE
! 289: END IF
! 290: 160 CONTINUE
! 291: 170 CONTINUE
! 292: ELSE
! 293: *
! 294: * Form C := alpha*A'*B' + beta*C
! 295: *
! 296: DO 200 J = 1,N
! 297: DO 190 I = 1,M
! 298: TEMP = ZERO
! 299: DO 180 L = 1,K
! 300: TEMP = TEMP + A(L,I)*B(J,L)
! 301: 180 CONTINUE
! 302: IF (BETA.EQ.ZERO) THEN
! 303: C(I,J) = ALPHA*TEMP
! 304: ELSE
! 305: C(I,J) = ALPHA*TEMP + BETA*C(I,J)
! 306: END IF
! 307: 190 CONTINUE
! 308: 200 CONTINUE
! 309: END IF
! 310: END IF
! 311: *
! 312: RETURN
! 313: *
! 314: * End of DGEMM .
! 315: *
! 316: END
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