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| author | jason <jason@8a072113-8704-0410-8d35-dd094bca7971> | 2008-10-28 01:38:50 +0000 |
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| committer | jason <jason@8a072113-8704-0410-8d35-dd094bca7971> | 2008-10-28 01:38:50 +0000 |
| commit | baba851215b44ac3b60b9248eb02bcce7eb76247 (patch) | |
| tree | 8c0f5c006875532a30d4409f5e94b0f310ff00a7 /SRC/sladiv.f | |
| download | lapack-baba851215b44ac3b60b9248eb02bcce7eb76247.tar.gz lapack-baba851215b44ac3b60b9248eb02bcce7eb76247.tar.bz2 lapack-baba851215b44ac3b60b9248eb02bcce7eb76247.zip | |
Move LAPACK trunk into position.
Diffstat (limited to 'SRC/sladiv.f')
| -rw-r--r-- | SRC/sladiv.f | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/SRC/sladiv.f b/SRC/sladiv.f new file mode 100644 index 00000000..f487d55c --- /dev/null +++ b/SRC/sladiv.f @@ -0,0 +1,62 @@ + SUBROUTINE SLADIV( A, B, C, D, P, Q ) +* +* -- LAPACK auxiliary routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + REAL A, B, C, D, P, Q +* .. +* +* Purpose +* ======= +* +* SLADIV performs complex division in real arithmetic +* +* a + i*b +* p + i*q = --------- +* c + i*d +* +* The algorithm is due to Robert L. Smith and can be found +* in D. Knuth, The art of Computer Programming, Vol.2, p.195 +* +* Arguments +* ========= +* +* A (input) REAL +* B (input) REAL +* C (input) REAL +* D (input) REAL +* The scalars a, b, c, and d in the above expression. +* +* P (output) REAL +* Q (output) REAL +* The scalars p and q in the above expression. +* +* ===================================================================== +* +* .. Local Scalars .. + REAL E, F +* .. +* .. Intrinsic Functions .. + INTRINSIC ABS +* .. +* .. Executable Statements .. +* + IF( ABS( D ).LT.ABS( C ) ) THEN + E = D / C + F = C + D*E + P = ( A+B*E ) / F + Q = ( B-A*E ) / F + ELSE + E = C / D + F = D + C*E + P = ( B+A*E ) / F + Q = ( -A+B*E ) / F + END IF +* + RETURN +* +* End of SLADIV +* + END |