izmax1.c
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00001 /* izmax1.f -- translated by f2c (version 20061008).
00002    You must link the resulting object file with libf2c:
00003         on Microsoft Windows system, link with libf2c.lib;
00004         on Linux or Unix systems, link with .../path/to/libf2c.a -lm
00005         or, if you install libf2c.a in a standard place, with -lf2c -lm
00006         -- in that order, at the end of the command line, as in
00007                 cc *.o -lf2c -lm
00008         Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
00009 
00010                 http://www.netlib.org/f2c/libf2c.zip
00011 */
00012 
00013 #include "f2c.h"
00014 #include "blaswrap.h"
00015 
00016 integer izmax1_(integer *n, doublecomplex *cx, integer *incx)
00017 {
00018     /* System generated locals */
00019     integer ret_val, i__1;
00020 
00021     /* Builtin functions */
00022     double z_abs(doublecomplex *);
00023 
00024     /* Local variables */
00025     integer i__, ix;
00026     doublereal smax;
00027 
00028 
00029 /*  -- LAPACK auxiliary routine (version 3.2) -- */
00030 /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
00031 /*     November 2006 */
00032 
00033 /*     .. Scalar Arguments .. */
00034 /*     .. */
00035 /*     .. Array Arguments .. */
00036 /*     .. */
00037 
00038 /*  Purpose */
00039 /*  ======= */
00040 
00041 /*  IZMAX1 finds the index of the element whose real part has maximum */
00042 /*  absolute value. */
00043 
00044 /*  Based on IZAMAX from Level 1 BLAS. */
00045 /*  The change is to use the 'genuine' absolute value. */
00046 
00047 /*  Contributed by Nick Higham for use with ZLACON. */
00048 
00049 /*  Arguments */
00050 /*  ========= */
00051 
00052 /*  N       (input) INTEGER */
00053 /*          The number of elements in the vector CX. */
00054 
00055 /*  CX      (input) COMPLEX*16 array, dimension (N) */
00056 /*          The vector whose elements will be summed. */
00057 
00058 /*  INCX    (input) INTEGER */
00059 /*          The spacing between successive values of CX.  INCX >= 1. */
00060 
00061 /* ===================================================================== */
00062 
00063 /*     .. Local Scalars .. */
00064 /*     .. */
00065 /*     .. Intrinsic Functions .. */
00066 /*     .. */
00067 /*     .. Statement Functions .. */
00068 /*     .. */
00069 /*     .. Statement Function definitions .. */
00070 
00071 /*     NEXT LINE IS THE ONLY MODIFICATION. */
00072 /*     .. */
00073 /*     .. Executable Statements .. */
00074 
00075     /* Parameter adjustments */
00076     --cx;
00077 
00078     /* Function Body */
00079     ret_val = 0;
00080     if (*n < 1) {
00081         return ret_val;
00082     }
00083     ret_val = 1;
00084     if (*n == 1) {
00085         return ret_val;
00086     }
00087     if (*incx == 1) {
00088         goto L30;
00089     }
00090 
00091 /*     CODE FOR INCREMENT NOT EQUAL TO 1 */
00092 
00093     ix = 1;
00094     smax = z_abs(&cx[1]);
00095     ix += *incx;
00096     i__1 = *n;
00097     for (i__ = 2; i__ <= i__1; ++i__) {
00098         if (z_abs(&cx[ix]) <= smax) {
00099             goto L10;
00100         }
00101         ret_val = i__;
00102         smax = z_abs(&cx[ix]);
00103 L10:
00104         ix += *incx;
00105 /* L20: */
00106     }
00107     return ret_val;
00108 
00109 /*     CODE FOR INCREMENT EQUAL TO 1 */
00110 
00111 L30:
00112     smax = z_abs(&cx[1]);
00113     i__1 = *n;
00114     for (i__ = 2; i__ <= i__1; ++i__) {
00115         if (z_abs(&cx[i__]) <= smax) {
00116             goto L40;
00117         }
00118         ret_val = i__;
00119         smax = z_abs(&cx[i__]);
00120 L40:
00121         ;
00122     }
00123     return ret_val;
00124 
00125 /*     End of IZMAX1 */
00126 
00127 } /* izmax1_ */


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autogenerated on Sat Jun 8 2019 18:55:50