Fix MSVC complex sqrt and packetmath test.

MSVC incorrectly handles `inf` cases for `std::sqrt<std::complex<T>>`.
Here we replace it with a custom version (currently used on GPU).

Also fixed the `packetmath` test, which previously skipped several
corner cases since `CHECK_CWISE1` only tests the first `PacketSize`
elements.

1 files changed, 6 insertions, 40 deletions

diff --git a/Eigen/src/Core/arch/CUDA/Complex.h b/Eigen/src/Core/arch/CUDA/Complex.h
index 69334cafe..ab0207cac 100644
--- a/Eigen/src/Core/arch/CUDA/Complex.h
+++ b/Eigen/src/Core/arch/CUDA/Complex.h
@@ -95,46 +95,12 @@ template<typename T> struct scalar_quotient_op<const std::complex<T>, const std:
 template<typename T> struct scalar_quotient_op<std::complex<T>, std::complex<T> > : scalar_quotient_op<const std::complex<T>, const std::complex<T> > {};
 
 template<typename T>
-struct sqrt_impl<std::complex<T>> {
-  static EIGEN_DEVICE_FUNC std::complex<T> run(const std::complex<T>& z) {
-    // Computes the principal sqrt of the input.
-    //
-    // For a complex square root of the number x + i*y. We want to find real
-    // numbers u and v such that
-    //    (u + i*v)^2 = x + i*y  <=>
-    //    u^2 - v^2 + i*2*u*v = x + i*v.
-    // By equating the real and imaginary parts we get:
-    //    u^2 - v^2 = x
-    //    2*u*v = y.
-    //
-    // For x >= 0, this has the numerically stable solution
-    //    u = sqrt(0.5 * (x + sqrt(x^2 + y^2)))
-    //    v = y / (2 * u)
-    // and for x < 0,
-    //    v = sign(y) * sqrt(0.5 * (-x + sqrt(x^2 + y^2)))
-    //    u = y / (2 * v)
-    //
-    // Letting w = sqrt(0.5 * (|x| + |z|)),
-    //   if x == 0: u = w, v = sign(y) * w
-    //   if x > 0:  u = w, v = y / (2 * w)
-    //   if x < 0:  u = |y| / (2 * w), v = sign(y) * w
-
-    const T x = numext::real(z);
-    const T y = numext::imag(z);
-    const T zero = T(0);
-    const T cst_half = T(0.5);
-
-    // Special case of isinf(y)
-    if ((numext::isinf)(y)) {
-      const T inf = std::numeric_limits<T>::infinity();
-      return std::complex<T>(inf, y);
-    }
-
-    T w = numext::sqrt(cst_half * (numext::abs(x) + numext::abs(z)));
-    return
-      x == zero ? std::complex<T>(w, y < zero ? -w : w)
-      : x > zero ? std::complex<T>(w, y / (2 * w))
-        : std::complex<T>(numext::abs(y) / (2 * w), y < zero ? -w : w );
+struct sqrt_impl<std::complex<T> >
+{
+  EIGEN_DEVICE_FUNC
+  static EIGEN_ALWAYS_INLINE std::complex<T> run(const std::complex<T>& x)
+  {
+    return complex_sqrt<T>(x);
   }
 };