zlassq.c
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00001 /* zlassq.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 /* Subroutine */ int zlassq_(integer *n, doublecomplex *x, integer *incx, 
00017         doublereal *scale, doublereal *sumsq)
00018 {
00019     /* System generated locals */
00020     integer i__1, i__2, i__3;
00021     doublereal d__1;
00022 
00023     /* Builtin functions */
00024     double d_imag(doublecomplex *);
00025 
00026     /* Local variables */
00027     integer ix;
00028     doublereal temp1;
00029 
00030 
00031 /*  -- LAPACK auxiliary routine (version 3.2) -- */
00032 /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
00033 /*     November 2006 */
00034 
00035 /*     .. Scalar Arguments .. */
00036 /*     .. */
00037 /*     .. Array Arguments .. */
00038 /*     .. */
00039 
00040 /*  Purpose */
00041 /*  ======= */
00042 
00043 /*  ZLASSQ returns the values scl and ssq such that */
00044 
00045 /*     ( scl**2 )*ssq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq, */
00046 
00047 /*  where x( i ) = abs( X( 1 + ( i - 1 )*INCX ) ). The value of sumsq is */
00048 /*  assumed to be at least unity and the value of ssq will then satisfy */
00049 
00050 /*     1.0 .le. ssq .le. ( sumsq + 2*n ). */
00051 
00052 /*  scale is assumed to be non-negative and scl returns the value */
00053 
00054 /*     scl = max( scale, abs( real( x( i ) ) ), abs( aimag( x( i ) ) ) ), */
00055 /*            i */
00056 
00057 /*  scale and sumsq must be supplied in SCALE and SUMSQ respectively. */
00058 /*  SCALE and SUMSQ are overwritten by scl and ssq respectively. */
00059 
00060 /*  The routine makes only one pass through the vector X. */
00061 
00062 /*  Arguments */
00063 /*  ========= */
00064 
00065 /*  N       (input) INTEGER */
00066 /*          The number of elements to be used from the vector X. */
00067 
00068 /*  X       (input) COMPLEX*16 array, dimension (N) */
00069 /*          The vector x as described above. */
00070 /*             x( i )  = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n. */
00071 
00072 /*  INCX    (input) INTEGER */
00073 /*          The increment between successive values of the vector X. */
00074 /*          INCX > 0. */
00075 
00076 /*  SCALE   (input/output) DOUBLE PRECISION */
00077 /*          On entry, the value  scale  in the equation above. */
00078 /*          On exit, SCALE is overwritten with the value  scl . */
00079 
00080 /*  SUMSQ   (input/output) DOUBLE PRECISION */
00081 /*          On entry, the value  sumsq  in the equation above. */
00082 /*          On exit, SUMSQ is overwritten with the value  ssq . */
00083 
00084 /* ===================================================================== */
00085 
00086 /*     .. Parameters .. */
00087 /*     .. */
00088 /*     .. Local Scalars .. */
00089 /*     .. */
00090 /*     .. Intrinsic Functions .. */
00091 /*     .. */
00092 /*     .. Executable Statements .. */
00093 
00094     /* Parameter adjustments */
00095     --x;
00096 
00097     /* Function Body */
00098     if (*n > 0) {
00099         i__1 = (*n - 1) * *incx + 1;
00100         i__2 = *incx;
00101         for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) {
00102             i__3 = ix;
00103             if (x[i__3].r != 0.) {
00104                 i__3 = ix;
00105                 temp1 = (d__1 = x[i__3].r, abs(d__1));
00106                 if (*scale < temp1) {
00107 /* Computing 2nd power */
00108                     d__1 = *scale / temp1;
00109                     *sumsq = *sumsq * (d__1 * d__1) + 1;
00110                     *scale = temp1;
00111                 } else {
00112 /* Computing 2nd power */
00113                     d__1 = temp1 / *scale;
00114                     *sumsq += d__1 * d__1;
00115                 }
00116             }
00117             if (d_imag(&x[ix]) != 0.) {
00118                 temp1 = (d__1 = d_imag(&x[ix]), abs(d__1));
00119                 if (*scale < temp1) {
00120 /* Computing 2nd power */
00121                     d__1 = *scale / temp1;
00122                     *sumsq = *sumsq * (d__1 * d__1) + 1;
00123                     *scale = temp1;
00124                 } else {
00125 /* Computing 2nd power */
00126                     d__1 = temp1 / *scale;
00127                     *sumsq += d__1 * d__1;
00128                 }
00129             }
00130 /* L10: */
00131         }
00132     }
00133 
00134     return 0;
00135 
00136 /*     End of ZLASSQ */
00137 
00138 } /* zlassq_ */


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autogenerated on Sat Jun 8 2019 18:56:41