On Thu, Nov 26, 2015 at 09:02:17PM +0500, Alexandr Shadchin wrote:
> From http://en.cppreference.com/w/c/numeric/complex/csqrt :
>
> csqrt(conj(z)) == conj(csqrt(z))
>
> Before patch
> csqrt(-4.0 + -0.0i) = 0.0 + 2.0j
> but should be
> csqrt(-4.0 + -0.0i) = 0.0 - 2.0j
This, too, looks right to me.
FWIW: ok tb@
>
> --
> Alexandr Shadchin
>
> Index: lib/libm/src/s_csqrt.c
> ===================================================================
> RCS file: /cvs/src/lib/libm/src/s_csqrt.c,v
> retrieving revision 1.6
> diff -u -p -r1.6 s_csqrt.c
> --- lib/libm/src/s_csqrt.c 3 Jul 2013 04:46:36 -0000 1.6
> +++ lib/libm/src/s_csqrt.c 24 Nov 2015 08:45:25 -0000
> @@ -79,7 +79,7 @@ csqrt(double complex z)
> r = fabs (x);
> r = sqrt (r);
> if (x < 0.0) {
> - w = 0.0 + r * I;
> + w = 0.0 + copysign(r, y) * I;
> }
> else {
> w = r + y * I;
> Index: lib/libm/src/s_csqrtf.c
> ===================================================================
> RCS file: /cvs/src/lib/libm/src/s_csqrtf.c,v
> retrieving revision 1.2
> diff -u -p -r1.2 s_csqrtf.c
> --- lib/libm/src/s_csqrtf.c 18 Jul 2010 18:42:26 -0000 1.2
> +++ lib/libm/src/s_csqrtf.c 24 Nov 2015 08:45:25 -0000
> @@ -72,7 +72,7 @@ csqrtf(float complex z)
>
> if(y == 0.0f) {
> if (x < 0.0f) {
> - w = 0.0f + sqrtf(-x) * I;
> + w = 0.0f + copysign(sqrtf(-x), y) * I;
> return (w);
> }
> else if (x == 0.0f) {
> Index: lib/libm/src/s_csqrtl.c
> ===================================================================
> RCS file: /cvs/src/lib/libm/src/s_csqrtl.c,v
> retrieving revision 1.2
> diff -u -p -r1.2 s_csqrtl.c
> --- lib/libm/src/s_csqrtl.c 20 Jul 2011 19:28:33 -0000 1.2
> +++ lib/libm/src/s_csqrtl.c 24 Nov 2015 08:45:25 -0000
> @@ -72,7 +72,7 @@ csqrtl(long double complex z)
>
> if (y == 0.0L) {
> if (x < 0.0L) {
> - w = 0.0L + sqrtl(-x) * I;
> + w = 0.0L + copysign(sqrtl(-x), y) * I;
> return (w);
> }
> else {
>
