stdlib_zrotg Subroutine
public pure subroutine stdlib_zrotg(a, b, c, s)
The computation uses the formulas |x| = sqrt( Re(x)2 + Im(x)2 ) sgn(x) = x / |x| if x /= 0 = 1 if x = 0 c = |a| / sqrt(|a|2 + |b|2) s = sgn(a) * conjg(b) / sqrt(|a|2 + |b|2) When a and b are real and r /= 0, the formulas simplify to r = sgn(a)sqrt(|a|2 + |b|*2) c = a / r s = b / r the same as in DROTG when |a| > |b|. When |b| >= |a|, the sign of c and s will be different from those computed by DROTG if the signs of a and b are not the same.
Arguments
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| complex(kind=dp), | intent(inout) | :: | a | |||
| complex(kind=dp), | intent(in) | :: | b | |||
| real(kind=dp), | intent(out) | :: | c | |||
| complex(kind=dp), | intent(out) | :: | s |