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/*! @file dzsum1.c
* \brief Takes sum of the absolute values of a complex vector and returns a double precision result
*
* <pre>
* -- LAPACK auxiliary routine (version 2.0) --
* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
* Courant Institute, Argonne National Lab, and Rice University
* October 31, 1992
* </pre>
*/
#include "slu_dcomplex.h"
#include "slu_Cnames.h"
/*! \brief
<pre>
Purpose
=======
DZSUM1 takes the sum of the absolute values of a complex
vector and returns a double precision result.
Based on DZASUM from the Level 1 BLAS.
The change is to use the 'genuine' absolute value.
Contributed by Nick Higham for use with ZLACON.
Arguments
=========
N (input) INT
The number of elements in the vector CX.
CX (input) COMPLEX*16 array, dimension (N)
The vector whose elements will be summed.
INCX (input) INT
The spacing between successive values of CX. INCX > 0.
=====================================================================
</pre>
*/
double dzsum1_slu(int *n, doublecomplex *cx, int *incx)
{
/* Builtin functions */
double z_abs(doublecomplex *);
/* Local variables */
int i, nincx;
double stemp;
#define CX(I) cx[(I)-1]
stemp = 0.;
if (*n <= 0) {
return stemp;
}
if (*incx == 1) {
goto L20;
}
/* CODE FOR INCREMENT NOT EQUAL TO 1 */
nincx = *n * *incx;
for (i = 1; *incx < 0 ? i >= nincx : i <= nincx; i += *incx) {
/* NEXT LINE MODIFIED. */
stemp += z_abs(&CX(i));
/* L10: */
}
return stemp;
/* CODE FOR INCREMENT EQUAL TO 1 */
L20:
for (i = 1; i <= *n; ++i) {
/* NEXT LINE MODIFIED. */
stemp += z_abs(&CX(i));
/* L30: */
}
return stemp;
/* End of DZSUM1 */
} /* dzsum1_slu */
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