Dasum Dasum_sub Daxpy Dcopy Ddot Ddot_sub Dnrm2 Dnrm2_sub Drot Drotg Drotm Drotmg Dscal Dswap

Drotg() Sub Drotg ( A As  Double, B As  Double, C As  Double, S As  Double  ) Constructs Givens plane rotation (BLAS 1) Purpose This routine constructs Givens plane rotation for the point (a, b) as below. ( c s ) * ( a ) = ( r ) ( -s c ) ( b ) ( 0 ) where r = sign(sqrt(a^2 + b^2), a), if |a| > |b|, r = sign(sqrt(a^2 + b^2), b), if |a| <= |b|, c^2 + s^2 = 1. The constructed plane rotation can be used by Drot to convert the points to the new coordinate system. Parameters [in,out] A [in] a value [out] r value [in,out] B [in] b value [out] z value   = s (if |a| > |b|)   = 1/c (|a| <= |b| and c != 0)   = 1 (if |a| <= |b| and c = 0)   = 0 (if r = 0) c and s can be reconstructed from z.   c = sqrt(1 - z^2), s = z (if z < 1)   c = 0, s = 1 (if z = 1)   c = 1/z, s = sqrt(1 - (1/z)^2) (if z > 1) [out] C c (cosine) value.   = a/r (if r <> 0)   = 1 (if r = 0) [out] S s (sine) value.   = b/r (if r <> 0)   = 0 (if r = 0) Reference BLAS