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haskell-igraph-0.8.0: igraph/src/idamax.c

/*  -- translated by f2c (version 20100827).
   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"

integer igraphidamax_(integer *n, doublereal *dx, integer *incx)
{
    /* System generated locals */
    integer ret_val, i__1;
    doublereal d__1;

    /* Local variables */
    integer i__, ix;
    doublereal dmax__;


/*  Purpose   
    =======   

       IDAMAX finds the index of element having max. absolute value.   

    Further Details   
    ===============   

       jack dongarra, linpack, 3/11/78.   
       modified 3/93 to return if incx .le. 0.   
       modified 12/3/93, array(1) declarations changed to array(*)   

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

       Parameter adjustments */
    --dx;

    /* Function Body */
    ret_val = 0;
    if (*n < 1 || *incx <= 0) {
	return ret_val;
    }
    ret_val = 1;
    if (*n == 1) {
	return ret_val;
    }
    if (*incx == 1) {

/*        code for increment equal to 1 */

	dmax__ = abs(dx[1]);
	i__1 = *n;
	for (i__ = 2; i__ <= i__1; ++i__) {
	    if ((d__1 = dx[i__], abs(d__1)) > dmax__) {
		ret_val = i__;
		dmax__ = (d__1 = dx[i__], abs(d__1));
	    }
	}
    } else {

/*        code for increment not equal to 1 */

	ix = 1;
	dmax__ = abs(dx[1]);
	ix += *incx;
	i__1 = *n;
	for (i__ = 2; i__ <= i__1; ++i__) {
	    if ((d__1 = dx[ix], abs(d__1)) > dmax__) {
		ret_val = i__;
		dmax__ = (d__1 = dx[ix], abs(d__1));
	    }
	    ix += *incx;
	}
    }
    return ret_val;
} /* igraphidamax_ */