DLARTG (3) - Linux Man Pages
subroutine dlartg (double precisionF, double precisionG, double precisionCS, double precisionSN, double precisionR)
DLARTG generates a plane rotation with real cosine and real sine.
DLARTG generate a plane rotation so that [ CS SN ] . [ F ] = [ R ] where CS**2 + SN**2 = 1. [ -SN CS ] [ G ] [ 0 ] This is a slower, more accurate version of the BLAS1 routine DROTG, with the following other differences: F and G are unchanged on return. If G=0, then CS=1 and SN=0. If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any floating point operations (saves work in DBDSQR when there are zeros on the diagonal). If F exceeds G in magnitude, CS will be positive.
F is DOUBLE PRECISION The first component of vector to be rotated.
G is DOUBLE PRECISION The second component of vector to be rotated.
CS is DOUBLE PRECISION The cosine of the rotation.
SN is DOUBLE PRECISION The sine of the rotation.
R is DOUBLE PRECISION The nonzero component of the rotated vector. This version has a few statements commented out for thread safety (machine parameters are computed on each entry). 10 feb 03, SJH.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
- September 2012
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