mirror of https://github.com/opencv/opencv.git
Open Source Computer Vision Library
https://opencv.org/
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
97 lines
2.2 KiB
97 lines
2.2 KiB
/* snrm2.f -- translated by f2c (version 20061008). |
|
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 "clapack.h" |
|
|
|
|
|
doublereal snrm2_(integer *n, real *x, integer *incx) |
|
{ |
|
/* System generated locals */ |
|
integer i__1, i__2; |
|
real ret_val, r__1; |
|
|
|
/* Builtin functions */ |
|
double sqrt(doublereal); |
|
|
|
/* Local variables */ |
|
integer ix; |
|
real ssq, norm, scale, absxi; |
|
|
|
/* .. Scalar Arguments .. */ |
|
/* .. */ |
|
/* .. Array Arguments .. */ |
|
/* .. */ |
|
|
|
/* Purpose */ |
|
/* ======= */ |
|
|
|
/* SNRM2 returns the euclidean norm of a vector via the function */ |
|
/* name, so that */ |
|
|
|
/* SNRM2 := sqrt( x'*x ). */ |
|
|
|
/* Further Details */ |
|
/* =============== */ |
|
|
|
/* -- This version written on 25-October-1982. */ |
|
/* Modified on 14-October-1993 to inline the call to SLASSQ. */ |
|
/* Sven Hammarling, Nag Ltd. */ |
|
|
|
|
|
/* .. Parameters .. */ |
|
/* .. */ |
|
/* .. Local Scalars .. */ |
|
/* .. */ |
|
/* .. Intrinsic Functions .. */ |
|
/* .. */ |
|
/* Parameter adjustments */ |
|
--x; |
|
|
|
/* Function Body */ |
|
if (*n < 1 || *incx < 1) { |
|
norm = 0.f; |
|
} else if (*n == 1) { |
|
norm = dabs(x[1]); |
|
} else { |
|
scale = 0.f; |
|
ssq = 1.f; |
|
/* The following loop is equivalent to this call to the LAPACK */ |
|
/* auxiliary routine: */ |
|
/* CALL SLASSQ( N, X, INCX, SCALE, SSQ ) */ |
|
|
|
i__1 = (*n - 1) * *incx + 1; |
|
i__2 = *incx; |
|
for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) { |
|
if (x[ix] != 0.f) { |
|
absxi = (r__1 = x[ix], dabs(r__1)); |
|
if (scale < absxi) { |
|
/* Computing 2nd power */ |
|
r__1 = scale / absxi; |
|
ssq = ssq * (r__1 * r__1) + 1.f; |
|
scale = absxi; |
|
} else { |
|
/* Computing 2nd power */ |
|
r__1 = absxi / scale; |
|
ssq += r__1 * r__1; |
|
} |
|
} |
|
/* L10: */ |
|
} |
|
norm = scale * sqrt(ssq); |
|
} |
|
|
|
ret_val = norm; |
|
return ret_val; |
|
|
|
/* End of SNRM2. */ |
|
|
|
} /* snrm2_ */
|
|
|