Mercurial > octave-nkf
diff libcruft/lapack/sladiv.f @ 7789:82be108cc558
First attempt at single precision tyeps
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corrections to qrupdate single precision routines
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prefer demotion to single over promotion to double
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Add single precision support to log2 function
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Trivial PROJECT file update
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Cache optimized hermitian/transpose methods
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Add tests for tranpose/hermitian and ChangeLog entry for new transpose code
| author | David Bateman <dbateman@free.fr> |
|---|---|
| date | Sun, 27 Apr 2008 22:34:17 +0200 |
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| children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/libcruft/lapack/sladiv.f Sun Apr 27 22:34:17 2008 +0200 @@ -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