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author | shmel1k <shmel1k@ydb.tech> | 2022-09-02 12:44:59 +0300 |
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committer | shmel1k <shmel1k@ydb.tech> | 2022-09-02 12:44:59 +0300 |
commit | 90d450f74722da7859d6f510a869f6c6908fd12f (patch) | |
tree | 538c718dedc76cdfe37ad6d01ff250dd930d9278 /contrib/libs/clapack/dlas2.c | |
parent | 01f64c1ecd0d4ffa9e3a74478335f1745f26cc75 (diff) | |
download | ydb-90d450f74722da7859d6f510a869f6c6908fd12f.tar.gz |
[] add metering mode to CLI
Diffstat (limited to 'contrib/libs/clapack/dlas2.c')
-rw-r--r-- | contrib/libs/clapack/dlas2.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/contrib/libs/clapack/dlas2.c b/contrib/libs/clapack/dlas2.c new file mode 100644 index 0000000000..1362a1a371 --- /dev/null +++ b/contrib/libs/clapack/dlas2.c @@ -0,0 +1,144 @@ +/* dlas2.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 "f2c.h" +#include "blaswrap.h" + +/* Subroutine */ int dlas2_(doublereal *f, doublereal *g, doublereal *h__, + doublereal *ssmin, doublereal *ssmax) +{ + /* System generated locals */ + doublereal d__1, d__2; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + doublereal c__, fa, ga, ha, as, at, au, fhmn, fhmx; + + +/* -- LAPACK auxiliary routine (version 3.2) -- */ +/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ +/* November 2006 */ + +/* .. Scalar Arguments .. */ +/* .. */ + +/* Purpose */ +/* ======= */ + +/* DLAS2 computes the singular values of the 2-by-2 matrix */ +/* [ F G ] */ +/* [ 0 H ]. */ +/* On return, SSMIN is the smaller singular value and SSMAX is the */ +/* larger singular value. */ + +/* Arguments */ +/* ========= */ + +/* F (input) DOUBLE PRECISION */ +/* The (1,1) element of the 2-by-2 matrix. */ + +/* G (input) DOUBLE PRECISION */ +/* The (1,2) element of the 2-by-2 matrix. */ + +/* H (input) DOUBLE PRECISION */ +/* The (2,2) element of the 2-by-2 matrix. */ + +/* SSMIN (output) DOUBLE PRECISION */ +/* The smaller singular value. */ + +/* SSMAX (output) DOUBLE PRECISION */ +/* The larger singular value. */ + +/* Further Details */ +/* =============== */ + +/* Barring over/underflow, all output quantities are correct to within */ +/* a few units in the last place (ulps), even in the absence of a guard */ +/* digit in addition/subtraction. */ + +/* In IEEE arithmetic, the code works correctly if one matrix element is */ +/* infinite. */ + +/* Overflow will not occur unless the largest singular value itself */ +/* overflows, or is within a few ulps of overflow. (On machines with */ +/* partial overflow, like the Cray, overflow may occur if the largest */ +/* singular value is within a factor of 2 of overflow.) */ + +/* Underflow is harmless if underflow is gradual. Otherwise, results */ +/* may correspond to a matrix modified by perturbations of size near */ +/* the underflow threshold. */ + +/* ==================================================================== */ + +/* .. Parameters .. */ +/* .. */ +/* .. Local Scalars .. */ +/* .. */ +/* .. Intrinsic Functions .. */ +/* .. */ +/* .. Executable Statements .. */ + + fa = abs(*f); + ga = abs(*g); + ha = abs(*h__); + fhmn = min(fa,ha); + fhmx = max(fa,ha); + if (fhmn == 0.) { + *ssmin = 0.; + if (fhmx == 0.) { + *ssmax = ga; + } else { +/* Computing 2nd power */ + d__1 = min(fhmx,ga) / max(fhmx,ga); + *ssmax = max(fhmx,ga) * sqrt(d__1 * d__1 + 1.); + } + } else { + if (ga < fhmx) { + as = fhmn / fhmx + 1.; + at = (fhmx - fhmn) / fhmx; +/* Computing 2nd power */ + d__1 = ga / fhmx; + au = d__1 * d__1; + c__ = 2. / (sqrt(as * as + au) + sqrt(at * at + au)); + *ssmin = fhmn * c__; + *ssmax = fhmx / c__; + } else { + au = fhmx / ga; + if (au == 0.) { + +/* Avoid possible harmful underflow if exponent range */ +/* asymmetric (true SSMIN may not underflow even if */ +/* AU underflows) */ + + *ssmin = fhmn * fhmx / ga; + *ssmax = ga; + } else { + as = fhmn / fhmx + 1.; + at = (fhmx - fhmn) / fhmx; +/* Computing 2nd power */ + d__1 = as * au; +/* Computing 2nd power */ + d__2 = at * au; + c__ = 1. / (sqrt(d__1 * d__1 + 1.) + sqrt(d__2 * d__2 + 1.)); + *ssmin = fhmn * c__ * au; + *ssmin += *ssmin; + *ssmax = ga / (c__ + c__); + } + } + } + return 0; + +/* End of DLAS2 */ + +} /* dlas2_ */ |