213 lines
6.1 KiB
C++
213 lines
6.1 KiB
C++
/* fortran/zlassq.f -- translated by f2c (version 20200916).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "lmp_f2c.h"
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/* > \brief \b ZLASSQ updates a sum of squares represented in scaled form. */
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/* =========== DOCUMENTATION =========== */
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/* Online html documentation available at */
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/* http://www.netlib.org/lapack/explore-html/ */
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/* > \htmlonly */
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/* > Download ZLASSQ + dependencies */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zlassq.
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f"> */
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/* > [TGZ]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zlassq.
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f"> */
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/* > [ZIP]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zlassq.
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f"> */
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/* > [TXT]</a> */
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/* > \endhtmlonly */
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/* Definition: */
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/* =========== */
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/* SUBROUTINE ZLASSQ( N, X, INCX, SCALE, SUMSQ ) */
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/* .. Scalar Arguments .. */
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/* INTEGER INCX, N */
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/* DOUBLE PRECISION SCALE, SUMSQ */
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/* .. */
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/* .. Array Arguments .. */
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/* COMPLEX*16 X( * ) */
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/* .. */
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/* > \par Purpose: */
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/* ============= */
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/* > */
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/* > \verbatim */
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/* > */
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/* > ZLASSQ returns the values scl and ssq such that */
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/* > */
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/* > ( scl**2 )*ssq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq, */
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/* > */
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/* > where x( i ) = abs( X( 1 + ( i - 1 )*INCX ) ). The value of sumsq is */
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/* > assumed to be at least unity and the value of ssq will then satisfy */
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/* > */
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/* > 1.0 .le. ssq .le. ( sumsq + 2*n ). */
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/* > */
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/* > scale is assumed to be non-negative and scl returns the value */
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/* > */
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/* > scl = max( scale, abs( real( x( i ) ) ), abs( aimag( x( i ) ) ) ), */
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/* > i */
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/* > */
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/* > scale and sumsq must be supplied in SCALE and SUMSQ respectively. */
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/* > SCALE and SUMSQ are overwritten by scl and ssq respectively. */
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/* > */
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/* > The routine makes only one pass through the vector X. */
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/* > \endverbatim */
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/* Arguments: */
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/* ========== */
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/* > \param[in] N */
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/* > \verbatim */
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/* > N is INTEGER */
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/* > The number of elements to be used from the vector X. */
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/* > \endverbatim */
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/* > */
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/* > \param[in] X */
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/* > \verbatim */
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/* > X is COMPLEX*16 array, dimension (N) */
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/* > The vector x as described above. */
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/* > x( i ) = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n. */
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/* > \endverbatim */
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/* > */
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/* > \param[in] INCX */
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/* > \verbatim */
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/* > INCX is INTEGER */
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/* > The increment between successive values of the vector X. */
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/* > INCX > 0. */
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/* > \endverbatim */
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/* > */
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/* > \param[in,out] SCALE */
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/* > \verbatim */
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/* > SCALE is DOUBLE PRECISION */
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/* > On entry, the value scale in the equation above. */
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/* > On exit, SCALE is overwritten with the value scl . */
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/* > \endverbatim */
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/* > */
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/* > \param[in,out] SUMSQ */
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/* > \verbatim */
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/* > SUMSQ is DOUBLE PRECISION */
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/* > On entry, the value sumsq in the equation above. */
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/* > On exit, SUMSQ is overwritten with the value ssq . */
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/* > \endverbatim */
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/* Authors: */
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/* ======== */
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/* > \author Univ. of Tennessee */
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/* > \author Univ. of California Berkeley */
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/* > \author Univ. of Colorado Denver */
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/* > \author NAG Ltd. */
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/* > \date December 2016 */
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/* > \ingroup complex16OTHERauxiliary */
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/* ===================================================================== */
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/* Subroutine */ int zlassq_(integer *n, doublecomplex *x, integer *incx,
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doublereal *scale, doublereal *sumsq)
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{
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/* System generated locals */
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integer i__1, i__2, i__3;
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doublereal d__1;
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/* Builtin functions */
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double d_imag(doublecomplex *);
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/* Local variables */
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integer ix;
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doublereal temp1;
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extern logical disnan_(doublereal *);
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/* -- LAPACK auxiliary routine (version 3.7.0) -- */
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/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
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/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
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/* December 2016 */
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/* .. Scalar Arguments .. */
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/* .. */
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/* .. Array Arguments .. */
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/* .. */
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/* ===================================================================== */
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/* .. Parameters .. */
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/* .. */
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/* .. Local Scalars .. */
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/* .. */
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/* .. External Functions .. */
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/* .. */
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/* .. Intrinsic Functions .. */
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/* .. */
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/* .. Executable Statements .. */
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/* Parameter adjustments */
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--x;
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/* Function Body */
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if (*n > 0) {
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i__1 = (*n - 1) * *incx + 1;
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i__2 = *incx;
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for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) {
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i__3 = ix;
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temp1 = (d__1 = x[i__3].r, abs(d__1));
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if (temp1 > 0. || disnan_(&temp1)) {
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if (*scale < temp1) {
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/* Computing 2nd power */
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d__1 = *scale / temp1;
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*sumsq = *sumsq * (d__1 * d__1) + 1;
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*scale = temp1;
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} else {
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/* Computing 2nd power */
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d__1 = temp1 / *scale;
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*sumsq += d__1 * d__1;
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}
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}
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temp1 = (d__1 = d_imag(&x[ix]), abs(d__1));
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if (temp1 > 0. || disnan_(&temp1)) {
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if (*scale < temp1) {
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/* Computing 2nd power */
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d__1 = *scale / temp1;
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*sumsq = *sumsq * (d__1 * d__1) + 1;
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*scale = temp1;
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} else {
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/* Computing 2nd power */
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d__1 = temp1 / *scale;
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*sumsq += d__1 * d__1;
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}
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}
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/* L10: */
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}
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}
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return 0;
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/* End of ZLASSQ */
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} /* zlassq_ */
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#ifdef __cplusplus
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}
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#endif
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