*DECK CDCDOT COMPLEX FUNCTION CDCDOT (N, CB, CX, INCX, CY, INCY) C***BEGIN PROLOGUE CDCDOT C***PURPOSE Compute the inner product of two vectors with extended C precision accumulation. C***LIBRARY SLATEC (BLAS) C***CATEGORY D1A4 C***TYPE COMPLEX (SDSDOT-S, CDCDOT-C) C***KEYWORDS BLAS, DOT PRODUCT, INNER PRODUCT, LINEAR ALGEBRA, VECTOR C***AUTHOR Lawson, C. L., (JPL) C Hanson, R. J., (SNLA) C Kincaid, D. R., (U. of Texas) C Krogh, F. T., (JPL) C***DESCRIPTION C C B L A S Subprogram C Description of Parameters C C --Input-- C N number of elements in input vector(s) C CB complex scalar to be added to inner product C CX complex vector with N elements C INCX storage spacing between elements of CX C CY complex vector with N elements C INCY storage spacing between elements of CY C C --Output-- C CDCDOT complex dot product (CB if N .LE. 0) C C Returns complex result with dot product accumulated in D.P. C CDCDOT = CB + sum for I = 0 to N-1 of CX(LX+I*INCY)*CY(LY+I*INCY) C where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is C defined in a similar way using INCY. C C***REFERENCES C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T. C Krogh, Basic linear algebra subprograms for Fortran C usage, Algorithm No. 539, Transactions on Mathematical C Software 5, 3 (September 1979), pp. 308-323. C***ROUTINES CALLED (NONE) C***REVISION HISTORY (YYMMDD) C 791001 DATE WRITTEN C 890531 Changed all specific intrinsics to generic. (WRB) C 890531 REVISION DATE from Version 3.2 C 891214 Prologue converted to Version 4.0 format. (BAB) C 920310 Corrected definition of LX in DESCRIPTION. (WRB) C 920501 Reformatted the REFERENCES section. (WRB) C***END PROLOGUE CDCDOT INTEGER N, INCX, INCY, I, KX, KY COMPLEX CX(*), CY(*), CB DOUBLE PRECISION DSDOTR, DSDOTI, DT1, DT2, DT3, DT4 C***FIRST EXECUTABLE STATEMENT CDCDOT DSDOTR = DBLE(REAL(CB)) DSDOTI = DBLE(AIMAG(CB)) IF (N .LE. 0) GO TO 10 KX = 1 KY = 1 IF(INCX.LT.0) KX = 1+(1-N)*INCX IF(INCY.LT.0) KY = 1+(1-N)*INCY DO 5 I = 1,N DT1 = DBLE(REAL(CX(KX))) DT2 = DBLE(REAL(CY(KY))) DT3 = DBLE(AIMAG(CX(KX))) DT4 = DBLE(AIMAG(CY(KY))) DSDOTR = DSDOTR+(DT1*DT2)-(DT3*DT4) DSDOTI = DSDOTI+(DT1*DT4)+(DT3*DT2) KX = KX+INCX KY = KY+INCY 5 CONTINUE 10 CDCDOT = CMPLX(REAL(DSDOTR),REAL(DSDOTI)) RETURN END