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/* lapack/complex16/zlassq.f -- translated by f2c (version 20050501).
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
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "v3p_netlib.h"
/*< SUBROUTINE ZLASSQ( N, X, INCX, SCALE, SUMSQ ) >*/
/* Subroutine */ int zlassq_(integer *n, doublecomplex *x, integer *incx,
doublereal *scale, doublereal *sumsq)
{
/* System generated locals */
integer i__1, i__2, i__3;
doublereal d__1;
/* Builtin functions */
double d_imag(doublecomplex *);
/* Local variables */
integer ix;
doublereal temp1;
/* -- LAPACK auxiliary routine (version 3.0) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
/* Courant Institute, Argonne National Lab, and Rice University */
/* June 30, 1999 */
/* .. Scalar Arguments .. */
/*< INTEGER INCX, N >*/
/*< DOUBLE PRECISION SCALE, SUMSQ >*/
/* .. */
/* .. Array Arguments .. */
/*< COMPLEX*16 X( * ) >*/
/* .. */
/* Purpose */
/* ======= */
/* ZLASSQ returns the values scl and ssq such that */
/* ( scl**2 )*ssq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq, */
/* where x( i ) = abs( X( 1 + ( i - 1 )*INCX ) ). The value of sumsq is */
/* assumed to be at least unity and the value of ssq will then satisfy */
/* 1.0 .le. ssq .le. ( sumsq + 2*n ). */
/* scale is assumed to be non-negative and scl returns the value */
/* scl = max( scale, abs( real( x( i ) ) ), abs( aimag( x( i ) ) ) ), */
/* i */
/* scale and sumsq must be supplied in SCALE and SUMSQ respectively. */
/* SCALE and SUMSQ are overwritten by scl and ssq respectively. */
/* The routine makes only one pass through the vector X. */
/* Arguments */
/* ========= */
/* N (input) INTEGER */
/* The number of elements to be used from the vector X. */
/* X (input) COMPLEX*16 array, dimension (N) */
/* The vector x as described above. */
/* x( i ) = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n. */
/* INCX (input) INTEGER */
/* The increment between successive values of the vector X. */
/* INCX > 0. */
/* SCALE (input/output) DOUBLE PRECISION */
/* On entry, the value scale in the equation above. */
/* On exit, SCALE is overwritten with the value scl . */
/* SUMSQ (input/output) DOUBLE PRECISION */
/* On entry, the value sumsq in the equation above. */
/* On exit, SUMSQ is overwritten with the value ssq . */
/* ===================================================================== */
/* .. Parameters .. */
/*< DOUBLE PRECISION ZERO >*/
/*< PARAMETER ( ZERO = 0.0D+0 ) >*/
/* .. */
/* .. Local Scalars .. */
/*< INTEGER IX >*/
/*< DOUBLE PRECISION TEMP1 >*/
/* .. */
/* .. Intrinsic Functions .. */
/*< INTRINSIC ABS, DBLE, DIMAG >*/
/* .. */
/* .. Executable Statements .. */
/*< IF( N.GT.0 ) THEN >*/
/* Parameter adjustments */
--x;
/* Function Body */
if (*n > 0) {
/*< DO 10 IX = 1, 1 + ( N-1 )*INCX, INCX >*/
i__1 = (*n - 1) * *incx + 1;
i__2 = *incx;
for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) {
/*< IF( DBLE( X( IX ) ).NE.ZERO ) THEN >*/
i__3 = ix;
if (x[i__3].r != 0.) {
/*< TEMP1 = ABS( DBLE( X( IX ) ) ) >*/
i__3 = ix;
temp1 = (d__1 = x[i__3].r, abs(d__1));
/*< IF( SCALE.LT.TEMP1 ) THEN >*/
if (*scale < temp1) {
/*< SUMSQ = 1 + SUMSQ*( SCALE / TEMP1 )**2 >*/
/* Computing 2nd power */
d__1 = *scale / temp1;
*sumsq = *sumsq * (d__1 * d__1) + 1;
/*< SCALE = TEMP1 >*/
*scale = temp1;
/*< ELSE >*/
} else {
/*< SUMSQ = SUMSQ + ( TEMP1 / SCALE )**2 >*/
/* Computing 2nd power */
d__1 = temp1 / *scale;
*sumsq += d__1 * d__1;
/*< END IF >*/
}
/*< END IF >*/
}
/*< IF( DIMAG( X( IX ) ).NE.ZERO ) THEN >*/
if (d_imag(&x[ix]) != 0.) {
/*< TEMP1 = ABS( DIMAG( X( IX ) ) ) >*/
temp1 = (d__1 = d_imag(&x[ix]), abs(d__1));
/*< IF( SCALE.LT.TEMP1 ) THEN >*/
if (*scale < temp1) {
/*< SUMSQ = 1 + SUMSQ*( SCALE / TEMP1 )**2 >*/
/* Computing 2nd power */
d__1 = *scale / temp1;
*sumsq = *sumsq * (d__1 * d__1) + 1;
/*< SCALE = TEMP1 >*/
*scale = temp1;
/*< ELSE >*/
} else {
/*< SUMSQ = SUMSQ + ( TEMP1 / SCALE )**2 >*/
/* Computing 2nd power */
d__1 = temp1 / *scale;
*sumsq += d__1 * d__1;
/*< END IF >*/
}
/*< END IF >*/
}
/*< 10 CONTINUE >*/
/* L10: */
}
/*< END IF >*/
}
/*< RETURN >*/
return 0;
/* End of ZLASSQ */
/*< END >*/
} /* zlassq_ */
#ifdef __cplusplus
}
#endif
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