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/* dsdot.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
#include "blaswrap.h"
doublereal dsdot_(integer *n, real *sx, integer *incx, real *sy, integer *
incy)
{
/* System generated locals */
integer i__1, i__2;
doublereal ret_val;
/* Local variables */
integer i__, ns, kx, ky;
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* AUTHORS */
/* ======= */
/* Lawson, C. L., (JPL), Hanson, R. J., (SNLA), */
/* Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL) */
/* Purpose */
/* ======= */
/* Compute the inner product of two vectors with extended */
/* precision accumulation and result. */
/* Returns D.P. dot product accumulated in D.P., for S.P. SX and SY */
/* DSDOT = sum for I = 0 to N-1 of SX(LX+I*INCX) * SY(LY+I*INCY), */
/* where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is */
/* defined in a similar way using INCY. */
/* Arguments */
/* ========= */
/* N (input) INTEGER */
/* number of elements in input vector(s) */
/* SX (input) REAL array, dimension(N) */
/* single precision vector with N elements */
/* INCX (input) INTEGER */
/* storage spacing between elements of SX */
/* SY (input) REAL array, dimension(N) */
/* single precision vector with N elements */
/* INCY (input) INTEGER */
/* storage spacing between elements of SY */
/* DSDOT (output) DOUBLE PRECISION */
/* DSDOT double precision dot product (zero if N.LE.0) */
/* REFERENCES */
/* ========== */
/* C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T. */
/* Krogh, Basic linear algebra subprograms for Fortran */
/* usage, Algorithm No. 539, Transactions on Mathematical */
/* Software 5, 3 (September 1979), pp. 308-323. */
/* REVISION HISTORY (YYMMDD) */
/* ========================== */
/* 791001 DATE WRITTEN */
/* 890831 Modified array declarations. (WRB) */
/* 890831 REVISION DATE from Version 3.2 */
/* 891214 Prologue converted to Version 4.0 format. (BAB) */
/* 920310 Corrected definition of LX in DESCRIPTION. (WRB) */
/* 920501 Reformatted the REFERENCES section. (WRB) */
/* 070118 Reformat to LAPACK style (JL) */
/* ===================================================================== */
/* .. Local Scalars .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* Parameter adjustments */
--sy;
--sx;
/* Function Body */
ret_val = 0.;
if (*n <= 0) {
return ret_val;
}
if (*incx == *incy && *incx > 0) {
goto L20;
}
/* Code for unequal or nonpositive increments. */
kx = 1;
ky = 1;
if (*incx < 0) {
kx = (1 - *n) * *incx + 1;
}
if (*incy < 0) {
ky = (1 - *n) * *incy + 1;
}
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
ret_val += (doublereal) sx[kx] * (doublereal) sy[ky];
kx += *incx;
ky += *incy;
/* L10: */
}
return ret_val;
/* Code for equal, positive, non-unit increments. */
L20:
ns = *n * *incx;
i__1 = ns;
i__2 = *incx;
for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) {
ret_val += (doublereal) sx[i__] * (doublereal) sy[i__];
/* L30: */
}
return ret_val;
} /* dsdot_ */
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