00001 /* dlapy3.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 doublereal dlapy3_(doublereal *x, doublereal *y, doublereal *z__) 00017 { 00018 /* System generated locals */ 00019 doublereal ret_val, d__1, d__2, d__3; 00020 00021 /* Builtin functions */ 00022 double sqrt(doublereal); 00023 00024 /* Local variables */ 00025 doublereal w, xabs, yabs, zabs; 00026 00027 00028 /* -- LAPACK auxiliary routine (version 3.2) -- */ 00029 /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ 00030 /* November 2006 */ 00031 00032 /* .. Scalar Arguments .. */ 00033 /* .. */ 00034 00035 /* Purpose */ 00036 /* ======= */ 00037 00038 /* DLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause */ 00039 /* unnecessary overflow. */ 00040 00041 /* Arguments */ 00042 /* ========= */ 00043 00044 /* X (input) DOUBLE PRECISION */ 00045 /* Y (input) DOUBLE PRECISION */ 00046 /* Z (input) DOUBLE PRECISION */ 00047 /* X, Y and Z specify the values x, y and z. */ 00048 00049 /* ===================================================================== */ 00050 00051 /* .. Parameters .. */ 00052 /* .. */ 00053 /* .. Local Scalars .. */ 00054 /* .. */ 00055 /* .. Intrinsic Functions .. */ 00056 /* .. */ 00057 /* .. Executable Statements .. */ 00058 00059 xabs = abs(*x); 00060 yabs = abs(*y); 00061 zabs = abs(*z__); 00062 /* Computing MAX */ 00063 d__1 = max(xabs,yabs); 00064 w = max(d__1,zabs); 00065 if (w == 0.) { 00066 /* W can be zero for max(0,nan,0) */ 00067 /* adding all three entries together will make sure */ 00068 /* NaN will not disappear. */ 00069 ret_val = xabs + yabs + zabs; 00070 } else { 00071 /* Computing 2nd power */ 00072 d__1 = xabs / w; 00073 /* Computing 2nd power */ 00074 d__2 = yabs / w; 00075 /* Computing 2nd power */ 00076 d__3 = zabs / w; 00077 ret_val = w * sqrt(d__1 * d__1 + d__2 * d__2 + d__3 * d__3); 00078 } 00079 return ret_val; 00080 00081 /* End of DLAPY3 */ 00082 00083 } /* dlapy3_ */