/*! @file izmax1.c

 * \brief Finds the index of the element whose real part has maximum absolute value

 *

 * 

 *     -- 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   

 * 

 */

#include <math.h></math.h>

#include "slu_dcomplex.h"

#include "slu_Cnames.h"

/*! \brief 

    Purpose   

    =======   

    IZMAX1 finds the index of the element whose real part has maximum   

    absolute value.   

    Based on IZAMAX from 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 >= 1.   

   ===================================================================== 

*/  

int

izmax1_(int *n, doublecomplex *cx, int *incx)

{

    /* System generated locals */

    int ret_val, i__1, i__2;

    double d__1;

    /* Local variables */

    double smax;

    int i, ix;

#define CX(I) cx[(I)-1]

    ret_val = 0;

    if (*n < 1) {

	return ret_val;

    }

    ret_val = 1;

    if (*n == 1) {

	return ret_val;

    }

    if (*incx == 1) {

	goto L30;

    }

/*     CODE FOR INCREMENT NOT EQUAL TO 1 */

    ix = 1;

    smax = (d__1 = CX(1).r, fabs(d__1));

    ix += *incx;

    i__1 = *n;

    for (i = 2; i <= *n; ++i) {

	i__2 = ix;

	if ((d__1 = CX(ix).r, fabs(d__1)) <= smax) {

	    goto L10;

	}

	ret_val = i;

	i__2 = ix;

	smax = (d__1 = CX(ix).r, fabs(d__1));

L10:

	ix += *incx;

/* L20: */

    }

    return ret_val;

/*     CODE FOR INCREMENT EQUAL TO 1 */

L30:

    smax = (d__1 = CX(1).r, fabs(d__1));

    i__1 = *n;

    for (i = 2; i <= *n; ++i) {

	i__2 = i;

	if ((d__1 = CX(i).r, fabs(d__1)) <= smax) {

	    goto L40;

	}

	ret_val = i;

	i__2 = i;

	smax = (d__1 = CX(i).r, fabs(d__1));

L40:

	;

    }

    return ret_val;

/*     End of IZMAX1 */

} /* izmax1_ */